add env variable

Issue-ID: INT-1217
Change-Id: Ibc46dc631edc2738b730d77c2a1c045c17d24dee
Signed-off-by: Brian Freeman <bf1936@att.com>
diff --git a/deployment/heat/onap-rke/onap-oom.yaml b/deployment/heat/onap-rke/onap-oom.yaml
index 2daf30a..effcd91 100644
--- a/deployment/heat/onap-rke/onap-oom.yaml
+++ b/deployment/heat/onap-rke/onap-oom.yaml
@@ -11,6 +11,10 @@
   apt_proxy:
     type: string
 
+  additional_override:
+    type: string
+    default: "master"
+
   public_net_id:
     type: string
     description: The ID of the Public network for floating IP address allocation