Followed this guide: https://docs.github.com/en/actions/creating-actions/creating-a-docker-container-action

The motivation behind this PR is to provide support in editors and prevent eroror / squiggly red line when using this action:

^ This error is due to missing action.yml. It still lets you use the action but doesn't provide you with any hints/autocomplete.

The action.yml file allows the official GitHub VSCode extension to provide descriptions and autocomplete when using the action. For example, here's the autocomplete support for actions/checkout@v3:

Is there a way an admin of this repo could create a next branch to merge this into instead of merging to master first? This is so I can further verify the types and autocomplete support (in addition to the testing I've done).
Once merged to next, I use the action like this:

# ...
uses: serverless/github-action@next
# ...

Then once all is good, I report back and request merge to master