Publish a container image of the authservice to whatever is the official image registry for istio-ecosystem projects

[cfryanr]

To make it easy for the community to try out the alpha version of the authservice, we would like to host the container image in some kind of public registry before releasing.

@liminw offered to find out what is the typical place where istio-ecosystem projects publish their container images for us.

[liminw]

I talked to a few folks who had repo in istio-ecosystem before. There is no standard way to publish container images in istio-ecosystem. The recommendation I got was, the maintainers of a repo should create a docker registry, and set up access control policies for the registry.

[tylerschultz]

The Pivotal team offered to take this issue.

[cfryanr]

How about we use the github container registry? It's free for open source projects.

See https://help.github.com/en/articles/about-github-package-registry

[peterhaochen47]

Just used github package to publish an image of authservice as of master as of this commit, which should include all the Alpha features of our project.

Here's the package page for authservice: https://github.com/istio-ecosystem/authservice/packages/42399