Improve Live Migration section in multinode-lab.rst

Added root user login check to ensure SSH keys exchanged.


Change-Id: I8513bc883ac273af8dcc2f61562a838d33b45a82
diff --git a/doc/source/guides/multinode-lab.rst b/doc/source/guides/multinode-lab.rst
index 8751eb8..a98c270 100644
--- a/doc/source/guides/multinode-lab.rst
+++ b/doc/source/guides/multinode-lab.rst
@@ -400,6 +400,10 @@
 
         ssh-keyscan -H DEST_HOSTNAME | sudo tee -a /root/.ssh/known_hosts
 
+3. Verify that login via ssh works without a password::
+
+        ssh -i /root/.ssh/id_rsa.pub stack@DESTINATION
+
 In essence, this means that every compute node's root user's public RSA key
 must exist in every other compute node's stack user's authorized_keys file and
 every compute node's public ECDSA key needs to be in every other compute