Document the proposals process in the GHC manual
The ghc-proposals process has proved robust, in my opinion. We should explicitly state that such a process exists and point users to it from the manual.
This came up as I was documenting the solution to #15743 (closed) in the manual. The end result there is very much a free design decision, and I wanted to invite readers to propose changes if they disagree with the design. But there's no good way to do so, currently.