Jim Bosch I've gone through and made v22 release notes for daf_butler, ctrl_mpexec, pipe_base, and obs_base and also changed the latter 3 to use towncrier for post-22. Please take a quick look and let me know if you think I've missed anything.

Yusra AlSayyad once I merge these will turn up on master for post-22 but you probably just want to scan quickly through the CHANGES.rst in each repo to see if there's anything you want in the global release notes.

Looks good; some minor comments on daf_butler, but I didn't have anything to say on the other packages.  I have not tried to exhaustively discover anything you might have missed, and my only big-picture concern is that I think many of the butler changes that were listed in other sections may have actually involved at least small API changes, while those that were marked as API changes may have only been backwards-compatible API additions.  I'm not really enthusiastic about trying to fix that retrospectively, because we haven't really been making hard API guarantees in daf_butler or even distinguishing super clearly between internal and public APIs.  But I think it might be time to get more serious about that going forward.  If you agree it's a future issue rather than a this-ticket issue, maybe it's something we should discuss at the meeting today.

I've moved the API section into new features.

I'm happy to evolve this over time. I'm fine with saving API changes for incompatible behavior changes. I had been using API to mean any API change because of Kian-Tat Lim's concern that he didn't want the public release notes to be full of detail that most users wouldn't care about. Having them in the API section on their own makes them easier to filter out. We can maybe work around that by saying that the release notes we build as part of these packages should be what we would expect an interested developer to want to know (just as if they were installing the package from pypi) and then assume that the official release notes will take what we've written and edit them down.

Oh, and I also don't have much motivation to go back and be super pedantic with the v22 release notes so punting the discussion out of this ticket is fine with me.