Add example docker-compose file to README

[YC]

Overview

Add example docker-compose file to README.

Testing recommendations

Should be relatively consistent with existing documentation.

GitHub issue number

N/A

Related Pull Requests

N/A

Checklist

• [x] Code is written and works correctly;
• [x] Changes are covered by tests;
• [x] Documentation reflects the changes;

[andrewfenn]

Please put this in. This project desperately needs it.