Make changeable contrail_vrouter_flow_hold_limit by salt.

Closes-Bug: PROD-20022
Change-Id: If414aae11527d344180638d8f24543ffb5de67aa
diff --git a/README.rst b/README.rst
index ba0d7b4..d7350c8 100644
--- a/README.rst
+++ b/README.rst
@@ -583,6 +583,7 @@
         version: 2.2
         enabled: True
         hostname: node-12.domain.tld
+        flow_hold_limit: 0
         discovery:
           host: 127.0.0.1
         interface: