Document the use of GitHub Actions/Workflows in OpenDRR

[anthonyfok]

We discussed in December 2021 and/or January 2022 that, as the usage of GitHub Actions workflows increase, that we should document them so that our team and the general public can better understand at a glance what they do and how they interact with one another.

There is a preliminary wiki page List of GitHub Actions in our projects, but it was last updated 28 May 2021 and severely incomplete and outdated.

Also, an automated script, or even a GitHub Actions workflow, to do a weekly scan all our OpenDRR archives for changes in .github/workflows, and maybe even generate statics such as whether they are run on a schedule, or triggered manually, or triggered vial a a webhook, and what actions are used, etc.