Merge pull request #314 from VillePihlava/add-docker-documentation

Add documentation about docker images

docs/index.md

@@ -45,6 +45,21 @@
 </dependencies>
 ```
 
+## Docker images
+
+There are automatically generated docker images available at https://registry.hub.docker.com/u/opentransitsoftwarefoundation.
+Contributions to image-specific documentation are welcome.
+
+### `onebusaway-gtfs-transformer-cli`
+
+See [the full documentation](./onebusaway-gtfs-transformer-cli.md) for more configuration options.
+
+For example, assuming that all the following files are in the `/path/to/local/data/directory` directory, to run the `remove-matching-route.rule` rule against `gtfs-data.zip` to generate `gtfs-data-out.zip` you can use:
+```bash
+docker run -v /path/to/local/data/directory:/data --rm opentransitsoftwarefoundation/onebusaway-gtfs-transformer-cli:4.4.0 --transform=/data/remove-matching-route.rule /data/gtfs-data.zip /data/gtfs-data-out.zip
+```
+The `gtfs-data-out.zip` file will be in the `/path/to/local/data/directory` directory.
+
 ## Example Code
 
 * Basic Reading