Fix broken rst links
Minor formatting/typo/doctest fixes
Remove workflow index

The overall structure is now provided in "How to contribute code" and the documents that were in the toctree for index are included elsewhere or linked to from the main index page.
Remove separate git configuration page

The only essentially piece -- setting user.name and user.email -- is included elsewhere.
Move section about cherry-picking

There are also a couple of link fixes/content cuts in here
Add several hidden toctrees to silence warnings