Docs

@wesleykendall Here is the pull request for docs. Like I said, I've been writing a lot of them. I still have one small section to finish, and I want to add some links in the quickstart documentation. I wanted to get this pull request out tonight, though.

@robdmc Once this is merged, there will be a pretty, readable version on readthedocs.org. Until then, though, you're welcome to read through the quickstart here if you were having any troubles.
I think it's sub_entity_kind now, right?