We currently keep docs on d.o and in version control. Since docs are tied to code, I feel that the authoritative source should most naturally our git repositories.
The suggestion would be to investigate how we can start deriving some degree of docs from files we commit to VCS, ideally written in a simple markup language like markdown.
Obviously this would require other very significant efforts in regards to UI changes and editability through the website, the latter of which is pretty daunting.
Anyhow, just tossing it out there :)