Incorrect instructions for using Docker containers

[jessebmiller]

I ran into two issues when trying to use the docker images on docker hub here https://hub.docker.com/r/holochain/holochain-proto/tags/.

First I expected to be able to run the container in the FROM line and look around but the repository name in the documentation /docker/README.md starts with a capital letter and I get the following.

❯ docker run -it Holochain/holochain-proto /bin/bash
docker: invalid reference format: repository name must be lowercase.
See 'docker run --help'.

Secondly the automated build only pushes a develop tag to docker hub and so I get the following after fixing the capital letter.

❯ docker run -it holochain/holochain-proto /bin/bash
Unable to find image 'holochain/holochain-proto:latest' locally
docker: Error response from daemon: manifest for holochain/holochain-proto:latest not found.
See 'docker run --help'.

I'd be happy to submit a PR to fix the documentation and add a push to holochain/holochain-proto:latest in CI if that's what folks want. Otherwise I could update the docs to use the develop tag.