Add Makefile as alternative to copying Docker cmds (#29)

Makefile

@@ -0,0 +1,10 @@
+all: build
+
+docker: Dockerfile
+	docker build --rm=true -t grrr .
+
+shell:
+	docker run -it -v "$(CURDIR):/grrr" --workdir=/grrr grrr /bin/bash
+
+
+.PHONY: docker shell

README.md

@@ -27,12 +27,20 @@ used to develop Golden Retriever. To use the container, first install Docker if
 not already available and start a Docker terminal. Then create the container by
 running the following build at the top level of the repository source tree:
 
+    make docker
+
+You can also manually invoke the docker command if you want to customize it:
+
     docker build --rm=true -t grrr .
 
 [Docker]: http://docker.io
 
 Once built, an interactive shell can be run in the container using:
 
+    make shell
+
+Again, if you want to customize the command invoked, use this as your base:
+
     docker run -it -v "$(pwd):/grrr" --workdir=/grrr grrr /bin/bash
 
 The current working directory from the host machine is available as the current