Create automated API documentation

[jsolly]

Context

It would be useful if there was some kind of auto-documentation a developer could visit to quickly see all the classes, functions, and what they do.

Eventually, we'll want handwritten examples, but this would be a good first step.

Thoughts

I like when projects have a 'readthedocs' link. Perhaps we can do that.

This documentation link should be able to be accessed from the GitHub readme and PyPi.