docs: add example to actionlint.yml

[patrickhuy]

Proposed Changes

1. The current template actionlint.yml does not provide any indication on how to specify available labels this adds a commented out example

Readiness Checklist

Author/Contributor

• If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance

[admiralAwkbar]

@patrickhuy thanks for catching this! Always good to give examples :)