Propose: move stable/docker-registry to this repo

As due to the helm/charts deprecation, the stable/docker-registry chart is now obsolete.

While it remains functional, new features or security measures are not being applied to it. As it is just a simple chart, maintenance of it should not be a problem.

Then, it could be advised and published on Artifact Hub as an official chart, which is cool. :)

https://github.com/helm/charts/tree/master/stable/docker-registry

What do the maintainers think?