Provide links for some documentation references

docs/src/AlgebraicGeometry/ToricVarieties/AlgebraicCycles.md

@@ -61,7 +61,7 @@ rational_equivalence_class(v::NormalToricVarietyType, p::MPolyQuoRingElem)
 rational_equivalence_class(v::NormalToricVarietyType, coefficients::Vector{T}) where {T <: IntegerUnion}
 ```
 
-### Special constructors
+### [Special constructors](@id toric_special_constructors)
 
 ```@docs
 rational_equivalence_class(d::ToricDivisor)
@@ -95,7 +95,7 @@ An algebraic cycle can be intersected `n`- with itself via `^n`,
 where `n` can be an integer of of type `ZZRingElem`.
 
 A closed subvarieties defines in a natural way a rational equivalence
-class (cf. section on special constructors above). This allows to
+class (cf. [Special constructors](@ref toric_special_constructors)). This allows to
 compute intersection products among closed subvarieties and rational
 equivalence classes in the Chow ring.
 

docs/src/CommutativeAlgebra/GroebnerBases/groebner_bases.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Gröbner/Standard Bases Over Fields
+# [Gröbner/Standard Bases Over Fields](@id gb_fields)
 
 We fix our notation in the context of standard (Gröbner) bases and present relevant OSCAR functions.
 
@@ -77,7 +77,7 @@ julia> default_ordering(S)
 wdegrevlex([x, y, z], [1, 2, 3])
 ```
 
-## Monomials, Terms, and More
+## [Monomials, Terms, and More](@id monomials_terms_more)
 
 Here are examples which indicate how to recover monomials, terms, and
 more from a given polynomial.
@@ -400,7 +400,7 @@ normal_form(g::T, I::MPolyIdeal; ordering::MonomialOrdering = default_ordering(b
 
 ## Syzygies
 
-We refer to the section on modules for more on syzygies.
+We refer to the section on [modules](@ref modules_multivariate) for more on syzygies.
 
 ```@docs
 syzygy_generators(G::Vector{<:MPolyRingElem})

docs/src/CommutativeAlgebra/GroebnerBases/groebner_bases_integers.md

@@ -33,7 +33,7 @@ julia> reduce(6*x, [5*x, 2*x])
 0
 ```
 
-The notion of *leading ideals*  as formulated in the previous section and the definitions of
+The notion of *leading ideals*  as formulated in [the previous section](@ref gb_fields) and the definitions of
 standard bases (Gröbner bases) carry over: A *standard basis* for an ideal $I\subset K[x]_>$
 with respect to $>$ is a finite subset $G$ of $I$ such that $\text{L}_>(G) = \text{L}_>(I)$ (a
 standard basis with respect to a global monomial ordering is also called a *Gröbner basis*).

docs/src/CommutativeAlgebra/GroebnerBases/orderings.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Monomial Orderings
+# [Monomial Orderings](@id monomial_orderings)
 
 Given a coefficient ring $C$ as in the previous section, let $C[x]=C[x_1, \ldots, x_n]$
 be the polynomial ring over $C$ in the set of variables $x=\{x_1, \ldots, x_n\}$. Monomials
@@ -37,7 +37,7 @@ A monomial ordering $>$ on $\text{Mon}_n(x)$ is called
 !!! note
     The lexicograpical monomial ordering specifies the default way of storing and displaying multivariate polynomials in OSCAR (terms are sorted in descending order).
     The other orderings which can be attached to a multivariate polynomial ring are the degree lexicographical ordering  and the degree reverse lexicographical
-    ordering. Independently of the attached orderings, Gröbner bases can be computed with respect to any monomial ordering. See the section on Gröbner bases.
+    ordering. Independently of the attached orderings, Gröbner bases can be computed with respect to any monomial ordering. See the section on [Gröbner bases](@ref gb_fields).
 
 In this section, we show how to create monomial orderings in OSCAR. 
 

docs/src/CommutativeAlgebra/Miscellaneous/binomial_ideals.md

@@ -31,7 +31,7 @@ While the first step can be performed over any ground field for which Gröbner b
 !!! note
     A *pure difference binomial* is a binomial which is the difference of two monomials. A *unital binomial ideal* is an ideal which can be generated by pure difference binomials and monomials. Note that cellular components of unital binomial ideals are unital as well. For unital binomial ideals in $\mathbb Q[x_1, \dots, x_n]$, binomial primary decompositions exist already over cyclotomic extensions of $\mathbb Q$. In particular, any such ideal can be decomposed over the abelian closure $\mathbb Q^{\text{ab}}$ of $\mathbb Q$. While OSCAR offers functionality for doing this, computing  binomial primary decompositions  in other cases is not yet supported. 
 
-    See the number theory chapter for how to deal with $\mathbb Q^{\text{ab}}$.
+    See the [number theory](@ref number_theory) chapter for how to deal with $\mathbb Q^{\text{ab}}$.
 !!! note
     Binomial primary decompositions computed with OSCAR are not necessarily minimal.
 

docs/src/CommutativeAlgebra/ModulesOverMultivariateRings/free_modules.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Free Modules
+# [Free Modules](@id free_modules)
 
 In this section, the expression *free module*  refers to a free module of finite rank
 over a ring of type `MPolyRing`, `MPolyQuoRing`, `MPolyLocRing`, or `MPolyQuoLocRing`.

docs/src/CommutativeAlgebra/ModulesOverMultivariateRings/intro.md

@@ -2,7 +2,7 @@
 CurrentModule = Oscar
 ```
 
-# Introduction
+# [Introduction](@id modules_multivariate)
 
 Our focus in this section is on finitely presented modules over rings from the following list:
 - multivariate polynomial rings (OSCAR type `MPolyRing`),
@@ -17,8 +17,8 @@ modules which naturally  includes both submodules and quotients of free modules.
 
 !!! note
     Most functions in this section rely on Gröbner (standard) bases techniques. Thus, the functions
-    should not be applied to modules over rings other than those from the list above. See the Linear
-    Algebra chapter for module types which are designed to handle modules over Euclidean
+    should not be applied to modules over rings other than those from the list above. See the [Linear
+    Algebra](@ref linear_algebra) chapter for module types which are designed to handle modules over Euclidean
     domains.
 
 !!! note

docs/src/CommutativeAlgebra/ModulesOverMultivariateRings/subquotients.md

@@ -34,7 +34,7 @@ Finally, we refer to
 and regard $M$ as a submodule of that ambient module, embedded in the natural way.
 
 !!! note
-    Recall from the section on free modules that by a free $R$-module we mean a free
+    Recall from the section on [free modules](@ref free_modules) that by a free $R$-module we mean a free
     module of type $R^p$ , where we think of $R^p$ as a free module with a given
     basis, namely the basis of standard unit vectors. Accordingly, elements of free modules
     are represented by coordinate vectors, and homomorphisms between free modules by

docs/src/CommutativeAlgebra/affine_algebras.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Affine Algebras and Their Ideals
+# [Affine Algebras and Their Ideals](@id affine_algebras)
 
 With regard to notation, we use *affine algebra* as a synonym for *quotient of a multivariate polynomial ring by an ideal*.
 More specifically, if $R$ is a multivariate polynomial ring with coefficient ring $C$, and $A=R/I$ is the quotient of $R$
@@ -14,14 +14,14 @@ discuss functionality for handling such algebras in OSCAR.
 
 !!! note
     To emphasize this point: In this section, we view $R/I$ together with its ring structure. Realizing $R/I$ as an
-    $R$-module means to implement it as the quotient of a free $R$-module of rank 1. See the section on modules.
+    $R$-module means to implement it as the quotient of a free $R$-module of rank 1. See the section on [modules](@ref modules_multivariate).
 
 !!! note
     Most functions discussed here rely on Gröbner basis techniques. In particular, they typically make use of a Gröbner basis for the
     modulus of the quotient. Nevertheless, the construction of quotients is lazy in the sense that the computation of such a Gröbner
     basis is delayed until the user performs an operation that indeed requires it (the Gröbner basis is then computed with respect
     to the monomial ordering entered by the user when creating the quotient; if no such ordering is entered, OSCAR will use the
-	`default_ordering` on the underlying polynomial ring; see the section on Gröbner/Standard Bases for default orderings in OSCAR).
+	`default_ordering` on the underlying polynomial ring; see the section on [Gröbner/Standard Bases](@ref gb_fields) for default orderings in OSCAR).
 	Once computed, the Gröbner basis is cached for later reuse.
 
 !!! note
@@ -31,7 +31,7 @@ discuss functionality for handling such algebras in OSCAR.
 !!! note
     In OSCAR, elements of a quotient $A = R/I$ are not necessarily represented by polynomials which are reduced with regard to $I$.
     That is, if $f\in R$ is the internal polynomial representative of an element of $A$, then $f$ may not be the normal form mod $I$
-    with respect to the default ordering on $R$ (see the section on *Gröbner/Standard Bases* for normal forms). Operations involving
+    with respect to the default ordering on $R$ (see the section on [Gröbner/Standard Bases](@ref gb_fields) for normal forms). Operations involving
     Gröbner basis computations may lead to (partial) reductions. The function `simplify` discussed in this section computes fully
     reduced representatives.
 

docs/src/CommutativeAlgebra/intro.md

@@ -2,7 +2,7 @@
 CurrentModule = Oscar
 ```
 
-# Introduction
+# [Introduction](@id commutative_algebra)
 
 The commutative algebra part of OSCAR provides functionality for dealing with
 
@@ -15,7 +15,7 @@ We use *affine algebra* as a synonym for *quotient of a multivariate polynomial
 
 Fundamental to computational commutative algebra is the concept of *standard bases*. Each such basis
 is defined relative to a *monomial ordering*. If this ordering is a well-ordering, a standard basis is also called
-a *Gröbner basis*. We refer to the corresponding section in this chapter for details.
+a *Gröbner basis*. We refer to the corresponding [section](@ref gb_fields) in this chapter for details.
 
 !!! note
     Each multivariate polynomial ring in OSCAR comes equipped with a monomial ordering according to which the

docs/src/CommutativeAlgebra/localizations.md

@@ -23,7 +23,7 @@ Mimicking the standard arithmetic for fractions, ``R[U^{-1}]`` can be made into
 \iota : R\to R[U^{-1}],\; r \mapsto \frac{r}{1}.
 ```
 Given an ``R``-module ``M``, the analogous construction yields an ``R[U^{-1}]``-module ``M[U^{-1}]`` which is
-called the *localization  of ``M`` at ``U``*. See the section on modules.
+called the *localization  of ``M`` at ``U``*. See the section on [modules](@ref modules_multivariate).
 
 Our focus in this section is on localizing multivariate polynomial rings and their quotients. The starting point
 for this is to provide functionality for handling (several types of) multiplicatively closed subsets of multivariate

docs/src/CommutativeAlgebra/rings.md

@@ -7,8 +7,9 @@ end
 
 # Creating Multivariate Rings
 
-In this section, for the convenience of the reader, we recall from the chapters on rings and fields
-how to create multivariate polynomial rings and their elements, adding illustrating examples.
+In this section, for the convenience of the reader, we recall from the chapters on
+[rings](@ref rings) and [fields](@ref fields) how to create multivariate polynomial
+rings and their elements, adding illustrating examples.
 At the same time, we introduce and illustrate a ring type for modelling multivariate polynomial
 rings with gradings.
 
@@ -432,7 +433,7 @@ Given an element `f` of a multivariate polynomial ring `R` or a graded version o
     the notion of total degree ignores the weights given to the variables in the graded case.
 
 For iterators which allow one to recover the monomials  (terms, $\dots$) of `f` we refer to the
-subsection *Monomials, Terms, and More* of the section on *Gröbner/Standard Bases*.
+subsection [Monomials, Terms, and More](@ref monomials_terms_more) of the section on [Gröbner/Standard Bases](@ref gb_fields).
 
 ###### Examples
 
@@ -502,5 +503,5 @@ refer to `R` and `S`, respectively.
 !!! note
     The OSCAR homomorphism type `AffAlgHom` models ring homomorphisms `R` $\to$ `S` such that
     the type of both `R` and `S`  is a subtype of `Union{MPolyRing{T}, MPolyQuoRing{U}}`, where `T <: FieldElem` and
-    `U <: MPolyRingElem{T}`. Functionality for these homomorphism is discussed in the section on affine algebras.
+    `U <: MPolyRingElem{T}`. Functionality for these homomorphism is discussed in the section on [affine algebras](@ref affine_algebras).
 

docs/src/DeveloperDocumentation/new_developers.md

@@ -75,7 +75,7 @@ in Julia. This will create a directory `~/.julia/dev/Oscar`. This directory is
 a git clone of the central OSCAR repository. You can develop your code here,
 however you will still have to fork OSCAR, as you have no rights to push to the
 central repository. You can then add your fork as another remote, have a look
-at the section on rebasing below for hints.
+at the section on [rebasing](@ref rebasing) below for hints.
 
 
 ## The edit process
@@ -160,7 +160,7 @@ naming conventions, code formatting, etc.
 To build and test the documentation, please have a look at [Documenting OSCAR
 code](@ref).
 
-### Rebasing
+### [Rebasing](@id rebasing)
 One way to stay up to date with the current master is rebasing. In order to do
 this, add the main Oscar.jl repository as a remote, fetch, and then rebase.
 ```

docs/src/Fields/intro.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Introduction
+# [Introduction](@id fields)
 
 The fields part of OSCAR provides functionality for handling
 various kinds of fields:

docs/src/InvariantTheory/finite_groups.md

@@ -5,7 +5,7 @@ DocTestSetup = Oscar.doctestsetup()
 
 # Invariants of Finite Groups
 
-In this section, with notation as in the introduction to this chapter, $G$ will be a *finite* group.
+In this section, with notation as in the [introduction](@ref invariant_theory) to this chapter, $G$ will be a *finite* group.
 
 !!! note
      The ssumption that $G$ is finite implies:

docs/src/InvariantTheory/intro.md

@@ -2,7 +2,7 @@
 CurrentModule = Oscar
 ```
 
-# Introduction
+# [Introduction](@id invariant_theory)
 
 The invariant theory part of OSCAR provides functionality for computing polynomial invariants
 of group actions, focusing on finite and linearly reductive groups, respectively.

docs/src/InvariantTheory/reductive_groups.md

@@ -4,7 +4,7 @@ CurrentModule = Oscar
 
 # Invariants of Linearly Reductive Groups
 
-In this section, with notation as in the introduction to this chapter,
+In this section, with notation as in the [introduction](@ref invariant_theory) to this chapter,
 $G$ will be a *linearly algebraic group* over an algebraically closed
 field $K$, $\rho: G \to \text{GL}(V)\cong \text{GL}_n(K)$ will
 be a *rational* representation of $G$, and

docs/src/InvariantTheory/tori.md

@@ -3,7 +3,7 @@ CurrentModule = Oscar
 ```
 
 # Invariants of Tori
-In this section, with notation as in the introduction to this chapter, $T =(K^{\ast})^m$ will be a torus of rank $m$
+In this section, with notation as in the [introduction](@ref invariant_theory) to this chapter, $T =(K^{\ast})^m$ will be a torus of rank $m$
 over a field $K$. To compute invariants of diagonal torus actions, OSCAR makes use of Algorithm 4.3.1  in [DK15](@cite) which,
 in particular, relies on algorithmic means from polyhedral geometry.
 

docs/src/LinearAlgebra/intro.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Introduction
+# [Introduction](@id linear_algebra)
 
 The linear algebra part of OSCAR provides functionality for handling
 - vectors and matrices

docs/src/NoncommutativeAlgebra/PBWAlgebras/intro.md

@@ -29,7 +29,7 @@ x_jx_i = c_{ij}x_ix_j+d_{ij}.
 ```
 
 Working with Gröbner bases requires that we take monomial orderings into account (see the section
-on Gröbner bases in the commutative algebra chapter for monomial orderings). In our context here, we use the following notation.
+on [Gröbner bases](@ref monomial_orderings) in the [commutative algebra](@ref commutative_algebra) chapter for monomial orderings). In our context here, we use the following notation.
 A *standard monomial* in $K \langle x \rangle$ is a word of type $x^\alpha=x_{1}^{\alpha_{1}}\cdots x_{n}^{\alpha_{n}},$
 where $\alpha=(\alpha_1,\dots,\alpha_n)\in\mathbb N^n$. A *standard polynomial* in $K \langle x \rangle$
 is a $K$-linear combination of standard monomials. Each global monomial ordering $>$ on $K[x]$ gives rise to

docs/src/NoncommutativeAlgebra/PBWAlgebras/quotients.md

@@ -7,7 +7,7 @@ end
 
 # GR-Algebras: Quotients of PBW-Algebras
 
-In analogy to the affine algebras section in the commutative algebra chapter, we describe OSCAR
+In analogy to the [affine algebras](@ref affine_algebras) section in the [commutative algebra](@ref commutative_algebra) chapter, we describe OSCAR
 functionality for dealing with quotients of PBW-algebras modulo two-sided ideals.
 
 !!! note

docs/src/NumberTheory/intro.md

@@ -2,7 +2,7 @@
 CurrentModule = Oscar
 ```
 
-# Introduction
+# [Introduction](@id number_theory)
 
 The number theory part of OSCAR provides functionality for algebraic number theory.
 

docs/src/Rings/intro.md

@@ -5,7 +5,7 @@ DocTestSetup = quote
 end
 ```
 
-# Introduction
+# [Introduction](@id rings)
 
 The rings part of OSCAR provides functionality for handling
 various kinds of rings: