Review: config-syntax documentation

dbr/Ben <b...@...>

Summary of the changes:

* Docs of the various sections within the config, and available transforms
* Basic guidelines for writing documentation (mainly I wanted somewhere to write the heading-underline convention)
* Layout tweak to add more padding on the right column, and better heading sizes
* Includes installation instructions using yum/Homebrew

You can view a combined version of the diffs in the "Files changed" tab, at the top of the page.
Main new file is: