Explain how to create the test VMs from vagrant

test/README.md

@@ -6,8 +6,13 @@ You need two VMs with docker >=1.3.1 installed and listening on TCP
 port 2375 (see below). You also need to be able to ssh to these VMs,
 preferably without having to input anything.
 
-The `Vagrantfile` in this directory constructs two such VMs. To meet
-the aforementioned ssh requirement you may want to
+The `Vagrantfile` in this directory constructs two such VMs.
+
+To create the VMs, open a shell and in this directory and type
+
+    vagrant up
+
+To meet the aforementioned ssh requirement you may want to
 
     cp ~/.vagrant.d/insecure_private_key .