Due to a bug in Sphinx [1], the ':noindex:' flag is currently broken for
the 'module' directive. Workaround it by replacing it with the ':no-index'
flag, which is what we'll need come Sphinx 9.x anyway.
[1] https://github.com/sphinx-doc/sphinx/issues/12843
Change-Id: If3fa5c51b566ea0144acf84d186ce12c8127c9a8
Also reorganizes the document structure to match both HTML and PDF docs.
Story: 2006100
Task: 35143
Change-Id: Ie3f38e2ecf52e6a6cbd52bb36196e6f589f1ca0f