Charm Quality Ratings updates

[Nick Veitch]

On Fri, Oct 4, 2013 at 12:28 PM, Mark Shuttleworth <mark at ubuntu.com> wrote:
>
> I think we'll need the ability both to document the interface in a particular charm, and to link to other charms
> interface docs from inside such documentation.

It is easy enough to do that by using Markdown, since we already
render that. Do we want it as a separate file? In many ways, it
*could* just be part of a well-written README, but then it isn't so
obvious where the information actually is.