Add exceptions to the EnsureWorkflows check + Docs Update

[feanil]

This check will make new PRs but there are times when we want to have certain repo/workflow exceptions where we don't want to mess with them from here and create extra churn. So add a way to track that info in the check so we can encode that info up front as we learn it.

Sample output:

docs.openedx.org: 
        Branch Protection with CLA Check is in Place. 'cla-checker' team has 'push' access.
        'openedx-triage' team has 'triage' access.
        All desired labels exist with the right name, color, description.
        All desired workflows are in sync with what's in the .github repo.
                Ignoring repo specific exceptions: ['commitlint.yml']
        No teams with `admin` or `maintain` permissions.
        All expected settings are set correctly.
        Steps:
                No changes needed.
        No user has direct repo access.

[sarina]

Thank you!