New approach to kill+destroy containers

After discussing with Randy, decided to take a different approach. No need to pass the results of the "docker-compose ps" command to docker. Docker-compose knows about any pertinent containers based on the .yml file; just let the command do its thing.

README.md

@@ -31,5 +31,5 @@ docker-compose stop
 
 #### Cleanup containers
 ```
-docker rm -f $(docker-compose ps -q)
+docker-compose rm -f
 ```