Handle dhcp_lease_duration option

Change-Id: I3b1a6ba31c55dde7e3e02e1eb3c46dddee515816
Closes-Bug: PROD-20880
diff --git a/README.rst b/README.rst
index 9cbd45a..d61d0f2 100644
--- a/README.rst
+++ b/README.rst
@@ -27,6 +27,7 @@
         rpc_workers: 2
         rpc_state_report_workers: 2
         root_helper_daemon: false
+        dhcp_lease_duration: 600
         bind:
           address: 172.20.0.1
           port: 9696
@@ -207,6 +208,7 @@
       gateway:
         enabled: True
         version: mitaka
+        dhcp_lease_duration: 600
         message_queue:
           engine: rabbitmq
           host: 127.0.0.1