Improve maintainers release workflow docs

[oberstet]

Feature Description

Improve maintainers release workflow docs in https://github.com/crossbario/autobahn-python/blob/master/docs/release-notes.rst

just download-github-release

✅ Found nightly release: master-202512150317

just docs
just docs-integrate-github-release master-202512150317
just generate-release-notes 25.12.2 master-202512150317
just prepare-changelog 25.12.2

=> integrate into docs/changelog.rst and docs/release-notes.rst

git commit -m "add release changelog & release-notes"
git push upstream

git tag -a v25.12.2 -m "tagged release"
git push --tags upstream

Checklist

• I have searched existing issues to avoid duplicates
• I have described the problem clearly
• I have provided use cases
• I have considered alternatives
• I have assessed impact and breaking changes