add md5 configuration support for bgp routers

Change-Id: I1e6bbc3ebd47bb9b4186e7891e6ab2b8a08af53a
diff --git a/README.rst b/README.rst
index 5f09362..a940cc6 100644
--- a/README.rst
+++ b/README.rst
@@ -984,6 +984,8 @@
           type: router
           ip_address: 172.16.0.22
           asn: 64512
+          key_type: md5
+          key: password
 
 Enforcing config nodes