message: add note in README.md about Docker deployment option
diff: @@ -44,6 +44,24 @@ The import process takes around 10 minutes to complete.
  node server.js // Default environment is development
  ```
  +### Running with Docker
  +
  +Postcodes.io is packaged as a Docker container identified on the Docker Hub as `james/postcodes.io`.
  +
  +```
  +docker run -d -p 8000 james/postcodes.io
  +```
  +
  +Configuration available via Environment Variables:
  +
  +- `MAPBOX_PUBLIC_KEY`
  +- `POSTGRES_USER`
  +- `POSTGRES_PASSWORD`
  +- `POSTGRES_DATABASE`
  +- `POSTGRES_HOST`
  +- `POSTGRES_PORT`
  +
  +
  ## Testing
  ```
  