Update this, or archive it and replace it with instructions in JIB

[vorburger]

I've stumbled upon this repo because it is the first hit on https://www.google.com/search?q=Gradle+Jib+plugin+and+google+cloud+build (at least for me) which I'm looking into for resolving https://github.com/vorburger/www.fineract.dev/issues/11.

But reading comments in https://gitter.im/google/jib?at=5dade0749825bd6baca1b398, about "Jib 1.5.0 and later, Jib will pick up credentials automatically from Google Cloud Builder" and "That coollog/jib-google-cloud-build is out-dated and you no longer need to link .docker/config.json." (both from Oct 23, 2019) make me suspect that the example in this repo is no longer current.

Would you be willing to update it? Do you have time to do it yourself, or would you merge a PR for it?

Or would you be willing to archive this repo and updating the README with a link to (the result of) https://github.com/GoogleContainerTools/jib/issues/3545?