Documentation on Docker Install Incorrect Missing Image

[gentoorax]

According to the documentation on installation via Docker, you can find the docker image on docker hub https://hub.docker.com/r/btcsuite/btcd

This is a dead link, and btcd doesn't exist on docker hub.

Documentation needs to be updated, but it would also be good to know if the image is available elsewhere, or do I need to build it? I'm deploying in k8s, so likely have to deploy my own registry without a reliable image reference.

[guggero]

See #2015. The documentation needs to be updated accordingly.