Summary of PR changes

Adding a workflow to test that pull_request triggered notifications appear as expected. I'm leaving it commented it out in case it comes in handy later.
Rename the Repository & branch property to Ref to better reflect what it is.
Fix the Ref url so it works and doesn't send the user to a 404 page.

PR Requirements

[X] For JavaScript actions, the action has been recompiled.
- See the Recompiling section of the repository's README.md for more details.
- This does not apply to Composite Run Steps actions unless a package.json is present and contains a build script.
[X] For major, minor, or breaking changes, at least one of the commit messages contains the appropriate +semver: keywords.
- See the Incrementing the Version section of the repository's README.md for more details.
[X] The examples in the repository's README.md have been updated with the new version.
- See the Incrementing the Version section of the repository's README.md for more details on how the version will be incremented.
[X] The action code does not contain sensitive information.