How to use the apko-publish action with an APK image built in a previous step?

[kastl-ars]

I am building a APK package, that is not (yet) included in Wolfi, in a Github Action.

After the package build, I would like to use that package in the apko-publish action to create an image using the local repository created by the previous step.

I have not found documentation on how to do that, unfortunately.

I got it working, so if someone wants to do something similar:
https://github.com/kastl-ars/wolfi-apkrane

Would you accept a PR adding an example to the README in the action's folder?

Kind Regards,
Johannes

P.S.: Thanks for creating all of the actions, especially apko-publish is really easy to use...