Improve README and example configuration #106
Description
Let's update our docs to describe configuring bayesrest using both a CGPM and a loom backend- the current README only describes how to use CGPM. We could include a commented template docker-compose.yml which shows examples of configurations (with one set commented out, perhaps).
We should also point out that it's possible to configure either in the .yaml file and/or using environment vars (and why the user may prefer one over the other in different deployments).
The current counties-demo repo has a good loom-backed configuration to take inspiration from.