Create documentation section for site

[karmatosed]

The basics this should include are:

• Template structure
• Guide to CSS structure

I personally do not feel this needs complex diagrams. We can do this simply. This comes from the following ticket:

Automattic/_s#709

[BrendanBerkley]

Wanted to make a note of support for this. I started a fresh copy of _s today - I love the theme, I've used it before, and am grateful for the work that has been done on it!

My big issue this time around is trying to figure out why it's laid out the way it is. I decided to comment when I realized that the layout folder doesn't compile into style.css along with everything else. Why compile them elsewhere, and why include commented-out @imports for those files in _site.scss?

I know ultimately I can do whatever I want, but I wanted to try and respect the structure and do things the Underscores way. Documentation would help with this!

[jmcbee]

I'm in the same position with @BrendanBerkley. When I downloaded a SASS version of the starter theme, I didn't quite understand why they are organized that way.

[gangstermath]

@karmatosed - While I appreciate your impulse to not overcomplicate things, a picture can still be worth a thousand words. I found this structural diagram of Thematic
https://web.archive.org/web/20110925022449/bluemandala.com/thematic/thematic-structure.html
early on, and it was a huge time saver every single time I did layout work.