Somewhat ironically, beanbag-docutils didn't have any real

documentation. There was in-code docs, and a README, but nothing beyond

that. We didn't even have release notes.
This change adds some formal docs that we can host on readthedocs.org.

It's primarily a collection of code reference docs (which already had

their own docs) and a list of release notes.
It's admittedly not very polished. Most of the content was taken from

the README or previous commits. Still, it will make it easier to keep

things maintained going forward.

Built the docs. Checked for build errors.
Skimmed through all the release notes and module docs for any

obvious issues.