Adds details about minimum docker compose version (#56)
Adds details about minimum docker compose version (#56)

This helps remove a problem when versions aren't quite right noticed by @jorgheymans 

```
~/src/brave-example$ PROJECT=armeria docker-compose up
ERROR: Invalid interpolation format for "frontend" option in service "services": "openzipkin/example-brave:${PROJECT:-armeria}"
```

https://docs.docker.com/compose/release-notes/#1190
kristofa/brave-resteasy-example