`release` event shows wrong `GITHUB_REF` definition

[jidicula]

Code of Conduct

• I have read and agree to the GitHub Docs project's Code of Conduct

What article on docs.github.com is affected?

https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#release

What part(s) of the article would you like to see updated?

GITHUB_REF actually points to the tag ref, not the tag itself, so it'll be the format refs/tags/<tag_name>, not tag_name.

Additional information

I'm opening a PR for fixing this too.