Release target tags and releases but CI also releases from tag

[headius]

I recently pushed new Psych gems and ran into confusion with the documented release instructions and the way things happen in reality.

The documentation says to use rake release to release the gem, which will tag the version, push the tag, and then build and push the gems.

However CI is also set up to automatically push release gems when the tag is pushed. This led to my local pushes conflicting with the CI pushes and that confusion led me to file rubygems/rubygems#8420.

I think we need to decide on one way or the other: either release in CI from the tag, or release from local environment after pushing the tag.

[hsbt]

After b9226fc, we could release a newer gem with git tag vXXX && git push --tags simply.

The workflow of trusted publisher will create and push Ruby and JRuby artifacts automatically. I sometimes forgot to push JRuby version of psych. The trusted publisher helps that my mistake.