Incorrect links in the doc

[fayolle]

Some of the links in the doc, in the 'Manifolds' section, seem to be incorrect:

• 'ManifoldsBase.jl' should point to https://juliamanifolds.github.io/ManifoldsBase.jl/stable/ instead of https://juliamanifolds.github.io/Manifolds.jl/stable/interface.html
• 'Notation' should point to https://juliamanifolds.github.io/Manifolds.jl/stable/misc/notation.html instead of https://juliamanifolds.github.io/Manifolds.jl/stable/notation.html

[kellertuer]

Thanks for pointing those out; indeed we moved those files in the other projects; ManifoldsBase.jl for example was first documented within Manifolds.jl (the old link) before it got its own documentation (the new link)

If you have the time feel free to open a PR; otherwise I will try to find time soon otherwise.

[kellertuer]

Thanks for the remarks, I carefully fixed the two links you mentioned throughout the documentation.