Add example of how to use actions in actions (aka. composite run steps)

[manovotny]

GitHub introduced something called composite run steps, which gave me such high hopes for abstracting repeatable steps that are used in multiple workflows.

For example, this would allow things like like cloning a repo, configuring node, installing / caching dependencies, etc. to be extracted into a referenceable YAML file and then "sucked into" in a test workflow and a release workflow, which both need to do all of those thing. This would help with the GitHub action copy / paste fatigue and help keep things DRY.

Unfortunately, this is not possible as you can't use uses (any many other things, as seen here and as mentioned in actions/runner#646). You can really only run shell commands, which is cool and a step in the right direction, but quite limiting. 😞

Sounds like GitHub is actively working on it, so here's to hoping! 🤞

[manovotny]

GitHub Actions: reusable workflows is generally available