Document the role of the setup-ruby release team and maintainers

Author: eregon

CONTRIBUTING.md

@@ -25,6 +25,24 @@ $ cp pre-commit .git/hooks/pre-commit
 This is entirely automated now since [this issue](https://github.com/ruby/setup-ruby/issues/254).
 If you do not see a new version more than 24 hours after it was released feel free to file an issue.
 
-## Release
+## Release team
 
-Maintainers can create a release automatically by running [this workflow](https://github.com/ruby/setup-ruby/actions/workflows/release.yml).
+The current release team is @eregon @MSP-Greg @ntkme @flavorjones @larskanis @headius.
+They all have write access to the `setup-ruby` repository, to be able to merge and release `ruby-builder-bot` PRs adding new versions.
+The `ruby-builder-bot` PRs are created by [this workflow](https://github.com/ruby/ruby-builder/actions/workflows/check-new-releases.yml) which runs every hour.
+
+The release team can create releases by running [this workflow](https://github.com/ruby/setup-ruby/actions/workflows/release.yml).
+
+The release team and more specifically @larskanis can run [the workflow to check for new RubyInstaller releases](https://github.com/ruby/setup-ruby/actions/workflows/check-new-windows-versions.yml) to speed things up (otherwise it's run twice a day).
+
+The release team must not merge other PRs than the ones from `ruby-builder-bot` (unless they are also setup-ruby maintainers).
+
+## Maintainers
+
+@eregon is the lead maintainer and creator of this action.
+Any design change (e.g. new input, different way to do things) must have his approval.
+
+@MSP-Greg @ntkme are maintainers of setup-ruby and should feel free to merge bug fixes, etc.
+They should request a review on their PR from another maintainer but they don't have to wait for the review if the fix is urgent (e.g. `setup-ruby` broke in some cases and the fix is obvious).
+
+Naturally maintainers can also [release setup-ruby](https://github.com/ruby/setup-ruby/actions/workflows/release.yml) so the changes from their PR get published.