Discrepancy between README and v0.1.2 compose.yaml configuration

The README's example of a docker compose yaml file (compose.yaml) makes no reference to the .env file or directory yet the compose.yaml file in the 0.1.2 tag of the code shows an entry for one.

```
    volumes:
      - ./.docker-data:/app/data
      - ./.env:/app/.env
```

Is .env needed?  If it is should this be a file or a directory?  Ie., should I `touch .env` or `mkdir .env`