Describe the bug:

We can improve the release process documentation a bit:

• add that the PR body should be empty?
• add more details on creating the release in GH, note that we should substitute the changelog with what we added to the tag (git tag -v vX.y.z).
• sort out how vX.x branch is updated since it's protected

To Reproduce

1. Follow CONTRIBUTING instructions to cut a release

Additional context

First batch of changes here #1989