I'd quite like to shift as much of the release related bumpf, like version numbers and release notes, onto branches rather than happening on master, as I think the current system is kind of complex and laden with traps...

this exists the way it does today because otherwise we'd have to publish different portions of the docsite from different places

Yeah, I'd be fine with docsite publishing running a few git commands to populate other branches release notes - it's just one file fetch per branch/tag... (I'd also be up for it just being generated from a single

git log

invocation if we had a convenient way to categorise commits, as a few people have been talking about...)