Release Docker image to gcr.io

[orgads]

Latest version on gcr.io is 1.1.0 from 09/2020.

Please publish newer releases.

Thanks.

This was requested in the past in #710 but I don't see that it was done.

[alexander-fenster]

Hi @orgads, thanks for noticing that - we'll do it this week. We stopped using docker in our production pipeline (we use Bazel for all languages we generate), that's why we never completely automated docker publishing. But we can surely publish new images for users who prefer running things in docker.

[orgads]

Thank you.

If building and running with bazel is easier than docker, consider updating the README.

[summer-ji-eng]

Updated the docker