Fill out some missing documentation to get our coverage back to 100%

Bring the docs up to 100% coverage.

Testing Done:
built the docs verified that `build/talkatu/reference/talkatu-undocumented.txt` has 100% coverage. Also ran the unit tests and demo to make sure nothing inadvertantly got busted.

Reviewed at https://reviews.imfreedom.org/r/91/