Update to reference rosetteapi/docker-python

- Removed docker directory
- Updated README

Author: Chris Park

README.md

@@ -81,6 +81,15 @@ The samples use the following procedure:
 
 See [examples](examples) for more request samples.
 
+## Docker ##
+A Docker image for running the examples against the compiled source library is available on Docker Hub.
+
+Command: `docker run -e API_KEY=api-key -v "<binding root directory>:/source" rosetteapi/docker-python`
+
+Additional environment settings:
+`-e ALT_URL=<alternative URL>`
+`-e FILENAME=<single filename>`
+
 API Documentation
 -----------------