Add Region api file

This is a first pass at a region.yaml file for the api

I listed the properties, functions, constructor, and extends. For the functions, I left out examples, descriptions, and emits. Examples and Descriptions I figured wouldn't tell us much about whether we liked it or not. Emits, I left out because I was lazy. I also left out param descriptions, but that can come later.

sidecomment - i tried to stick with jsdoc and dox conventions