Updates to Docker build and README

[ashelkovnykov]

• Updates README (here and in DockerHub)
• Fixes bug that posted README updates to tloncorp/urbit instead of tloncorp/vere
• Moves DockerHub deploy tasks in build to separate workflow
• Adds a workflow which allows on-demand GitHub Action to redeploy Docker image to DockerHub

[mopfel-winrux]

Can we also include click.sh in the docker container? It would make maintaining piers a lot easier

[ashelkovnykov]

@mopfel-winrux I'm not sure what the best way to do that is. The plan was to move the click stuff to a separate tools repo, but that becomes an issue if we want to do both:
a) build a new Docker image for each commit
b) include click in that Docker image

[mopfel-winrux]

@ashelkovnykov hmm yea that is a conflict. I think if we're going to try and deprecate %lens it would make sense to include instructions either how to side-load click into the docker container through the volume, or to include it in it. I'm fine with either. NP sideloads scripts regularly into docker containers.