Currently the details for the release PR are only created with the -push flag.

That means if a library maintainer wants to edit the release notes, they either have to work out exactly what librarian would have done, or push a PR, then fetch the branch and modify it.

I don't think this needs to block migration immediately, but we should have a simpler process soon.

Possible remedies:

• When -push isn't specified, log what the PR title and description would have been so that maintainers can copy/paste it
• Use the commit message instead of the PR title/description, so that maintainers can use the -commit flag, then create another commit afterwards, and let the manual PR creation flow "just work", modulo adding the right label. (Although librarian: -commit still tries to push to GitHub #2390 is blocking this.)