This has been brought up before (#8603), but I think it's time to create a tracking issue.

We have a number of problems with how we currently manage release notes:

• They frequently create merge conflicts which are frustrating for everyone to rebase
• If a PR does not make it into its intended release, the PR is unmergeable until someone gets around to moving the release notes
• If a PR is scheduled for a future version that isn't the next release, there's no way to write the release notes at all until it becomes the "current" release
• Backported PRs requires manual reassembly of release notes

All of these would be fixed by a "one file per section" approach to release notes, which matches what matplotlib and cpython do.

Some options:

• Do the merge manually (via cat or similar?) like matplotlib does
• Use blurb, which is what cpython does
• Use towncrier, which has been suggested in the past

Some advantages of what we already do:

• It's typically possible to blame the release notes to find the patch that introduced the change
• You can read the master release notes in a single place. We could probably achieve this in the dev-docs anyway though.