Initial docker-compose file for easy setup with InspIRCd

- We now have a docker-compose.yml, which will automatically provision
  an InspIRCd docker container alongside an sms-irc one and handle all
  the linking for you, such that you only have to give it a postgres
  database, deal with its files, and you can connect to an IRC port!
- However, some work could still be done to document it a bit better.