Kh documentation

@boonrs integrated the documentation using markdown. Things I'm holding off on ...

- linking to 311 data in the research and references section (want to find a way to present this data)
- screenshots of the app (waiting for the geocoding stuff to get sorted out)

Also, feel free to add a better description of the API and what it does. I just through some rough text in there. 



Nice work :flags: 
Should we also link to project press?