Add edge docs and document some of the recent changes in edge

This adds a non-numbered edge version that can be updated without worrying about messing with latest docs. I think that matches the cdn and jsfiddle conventions a little bit better.

I've also taken a stab at documenting some of the latest changes in edge. If someone could take a look at this, especially the container/parent stuff, to make sure this isn't seriously wrong/misleading, I would be appreciative :-)

At some point in the not-too-distant future, I'd like to take a stab at using Ractive, page.js, and marked to do the docs site. I think it would be nice to have some examples with some level of interactivity.