documentation about how cabal (as a protocol) works

[todrobbins]

per hangyas question on the public cabal:

hi, is there any documentation about how does cabal (as a protocol) work? (i understand dat fairly good)

It would be great to produce some overviews for the website about how cabal works.

[epragalakis]

^ 👍🏼 on that.
Also it will be good to list all the available commands that are available on cabal desktop.
eg: Changing your username etc..
And maybe what cabal is lacking - but the user expects to find? Like avatars and private messages?