Remove Markdown definition lists from embedded docs

A long time ago, I shortsightedly decided to use the definition list Markdown
extension in some of our docs. Time and the renderer ecosystem haven't been kind
to that syntax, so we need to get away from them if we want to be able to switch
relatively freely between various MD processors.

This commit removes them from the last embedded documentation that we still use.
The old-style type reference still uses them, but since we've stopped relying on
it and moved to our own implementation, that should be fine.

If you're inside the VPN, you can see what the reformatted indirection reference looks like here:
http://docspreview3.puppetlabs.lan/indirection2.html --The changes should also hopefully make the table of contents more useful, albeit still like a mile long and kinda messy.