[request] Document `newTag` output and how to consume it

[douglasg14b]

I was able to find this in the code by searching for >> $GITHUB_OUTPUT, but not many folks will know how to find this information.

Documenting the output and how to consume it would probably help a lot of people who need to perform their own commit & tag (ie. if they need to sync this version bump across different files before making a commit)

[phips28]

I would appreciate if you could do a PR for the docs 🙂

[douglasg14b]

I really don't know what to add to the docs here, I'm not the author, and am similarly struggling to use it.

For reference:

gh-action-bump-version/index.js

Line 233 in fdad52b

await runInWorkspace('sh', ['-c', `echo "newTag=${newVersion}" >> $GITHUB_OUTPUT`]);

[Asim-Tahir]

Done at #271. Can i have a review for it, thx