- Added chapter about media type negotiation.
- Added instructions on how to install dependencies for the audio media
type.
- Moved part about how to enable media types in your config to a single
place at the top of the document named "Enable Media Types".
- Renamed the "Enable Media Types" page to "Media Types".
Adds a summary and a link to the wiki for contributors to the front page.
The "what is mediagoblin" section in the about chapter talkd about what
it was, but it was buried--this slightly unburies it.
* create initial bits for plugin writer's guide
* move siteadmin stuff to site administrator's guide
* rework index.rst to support multiple guides
* tweak some text
* move files into subdirectories
I verified that this still works with html and texinfo build targets.
There's still a lot of work to do, but this is a good start.
