Rename faq/faq.rst to faq/index.rst and deduplicate TOCs
The FAQ was put in a single file in faq/faq.rst as a hack, using multiple top-level headers in the same file to make them appear in the global TOC.
With this change, the TOC is moved to the index.rst file, with a single top-level header, and uses a local TOC instead, as it should be.
Additionally, this removed the manually-written TOC in the main index to use an auto-generated one.
Before:
After:
Migrated from D5922 (view on Phabricator)