Request: GitHub Actions Workflow syntax

[allejo]

I'm willing to work on generating a set of docs for this but I'd like some feedback on what other people would want/need from this set: https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions

I really need the spec for each of the YAML keys allowed in a workflow file. Is this that enough? Is there anything else others would want to see included as well?