toc start at value don't always behave as expected

[mojavelinux]

The expectation is that if the page numbering or running content start at value is set to toc, the respective feature will start at the first page of the TOC.

Here are the scenarios that are not working as expected:

• start at is toc and toc placement is macro (both page numbering and running content)
• start at is toc and toc placement is preamble (both page numbering and running content)
• index entry page numbers when page numbering start at is toc

Here's a reproducible example:

= Book Title
:doctype: book
:toc: macro
:media: prepress

[colophon%notitle]
== Dedication

Credit where credit is due.

toc::[]

== Start

Let's go.

== Finish

Let's wrap this up.

This example is expected to be used with a theme that configures the page numbering to start at the toc:

extends: default
page-numbering:
  start-at: toc

The documentation should also be updated to emphasize that the toc and after-toc start at values are really only intended to be used with the book doctype (though they do work with the article doctype if the title page is enabled). Also emphasize that for a prepress book, the after-toc value maps to the first recto page that follows the TOC.