stop claiming Twitter is sole doc author. fix sphinx warnings

This change started out as fixing up a couple of (unused) Sphinx-doc config settings; If we ever exercised those settings, they woulda claimed Twitter was sole docs author. Not true nope nope nope.

While making sure that I didn't break Sphinx, I went on a warning-squishing rampage.

Testing Done:
./build-support/bin/publish_docs.sh

Reviewed at https://rbcommons.com/s/twitter/r/729/