Enabled Overlay Encryption docker containers.

Change-Id: I0b63ccc7600fcd7b08af7acaf9399407bd618463
diff --git a/compose/docker-compose-kafka-cluster.yml b/compose/docker-compose-kafka-cluster.yml
index e1d555c..b850932 100644
--- a/compose/docker-compose-kafka-cluster.yml
+++ b/compose/docker-compose-kafka-cluster.yml
@@ -58,6 +58,8 @@
 networks:
     net:
         driver: overlay
+        driver_opts:
+           encrypted: "true"
 
     voltha-net:
         external: