Generate python documentation without requiring compilation

[virtuald]

We can't easily build these modules on readthedocs -- and honestly, we probably don't want to anyways. Instead, if we had an rst generator template, then readthedocs could just run that and then we'd have docs.

This seems easier than trying to get sphinx to read from pyi files -- and the pyi files would have references to other non-installed modules (which aren't really required to create documentation), so the imports would fail.

Maybe @auscompgeek has a better idea?