RELEASE.md rewrite

[Lorak-mmk]

RELEASE.md contained outdated procedures which were not useful to a person that wanted to perform a release. To avoid explaining manually how to do a release again and again I've rewritten this file with current information about release process and other maintenance-related stuff with much more detail than before.

It should aid current and future maintainers during any releases.

I've also changed triggers on docs generation workflow - commit message explains why.

Pre-review checklist

• [x] I have split my patch into logically separate commits.
• [x] All commit messages clearly explain what they change and why.
• [ ] I added relevant tests for new features and bug fixes.
• [x] All commits compile, pass static checks and pass test.
• [x] PR description sums up the changes and reasons why they should be introduced.
• [ ] I have provided docstrings for the public items that I want to introduce.
• [ ] I have adjusted the documentation in ./docs/source/.
• [ ] I added appropriate Fixes: annotations to PR description.

[Lorak-mmk]

@piodul @wprzytula Please read the doc and verify that all information are correct.

@muzarski @dkropachev as you are not mainteiners I'd appreciate if you read the doc to check that everything in understandable for person not familiar with maintenance processes of this project.

[github-actions[bot]]

cargo semver-checks found no API-breaking changes in this PR! 🎉🥳 Checked commit: 286786b539ee2d347a7425485d6462c1dc07e434

[Lorak-mmk]

v2:

• Addressed review comments
• Added section about writing release notes: what to include and how, how to count commits by author etc

[Lorak-mmk]

v3: Addressed review comments, changed the release notes guidelines according to @wprzytula suggestion