Update README.md

Author: jeffmaki

README.md

@@ -19,6 +19,8 @@
 
 # To build images
 
+```git clone --recursive https://github.com/TaskarCenterAtUW/workspaces-stack.git```
+
 ```docker-compose -f docker-compose.build.yml --env-file XXX.env build```
 
 Replace XXX.env with the environment definition file of the environment for which you want to build an image. This can be overridden when running (see below).