Update README.md

Added docker logs command. Useful for debugging problems.

README.md

@@ -71,6 +71,8 @@ docker container rm     # remove container
 docker container kill     # kill a running container
 docker system prune       # Remove all unused docker: containers, images, networks and volumes to free up space
 docker container prune    # Similar to system prune but only targets containers.
+docker logs CONTAINERNAME # Shows logs for the container
+docker logs --follow CONTAINERNAME # Shows log for the container in the foreground
 
 ### While inside app specific folder
 docker-compose restart  # restart docker stack for application