Set up docker deployment to a staging server

[dustin-jw]

Our deploy.docker.yml workflow handles everything up to publishing the container to a registry, but it stops short of actually deploying the image to a server. It would be helpful for the starter to cover the end-to-end process for this workflow for typical use cases. If we have a Rackspace or Digital Ocean instance to test with, it would be good to get that set up so we can update the workflow and write more comprehensive documentation about how to get set up with this hosting strategy.

This should include:

• Updating documentation to describe how to authenticate to ghcr.io from the server
• Adding a docker-compose.production.yml file to simplify restarting after pulling the image
• Updating docs to describe what files need to be set up on the server (mainly .env with relevant DB info and docker-compose.yml copied from the production version)
• Updating docs to describe how to pull the image and run it for first time setup
• Adding steps to the deploy.docker.yml workflow to pull/restart the image and document any secrets that need to be set for it to work