CORD-616 some cleanup and clarification about registry tags

Change-Id: Ia8562b8b17c949fe135b8092fa370733629e039c
diff --git a/roles/head-node/tasks/main.yml b/roles/head-node/tasks/main.yml
index 1d85d03..62b7766 100644
--- a/roles/head-node/tasks/main.yml
+++ b/roles/head-node/tasks/main.yml
@@ -121,3 +121,4 @@
     - cord-prov
     - cord-switch
     - cord-generate
+    - cord-registry