Ahodges/doc/doc 792

Initial, proof of concept draft, focusing initially on enrollment chapters. @shnayder , @clintonb , @dsjen , @mulby , @brianhw , @rocha , @JAAkana , @WatsonEmily , @stroilova please feel free to comment anytime on this PR from now through release.

An HTML draft is now available! http://draft-edx-insights.readthedocs.org/en/latest/

Not sure if we can do anything about this, but a styling note: there is less space above the bulleted line than below it, which visually connects the wrong things (term with the definition for the previous one).  If we control the css at all, may be easy to fix.