OCPBUGS-16200: updates SDN to OVN-K migration with AWS specific prerequisites

Author: JoeAldinger

modules/nw-ovn-kubernetes-migration.adoc

@@ -24,6 +24,7 @@ Perform the migration only when an interruption in service is acceptable.
 * A recent backup of the etcd database is available.
 * A reboot can be triggered manually for each node.
 * The cluster is in a known good state, without any errors.
+* On all cloud platforms after updating software, a security group rule must be in place to allow UDP packets on port `6081` for all nodes.
 
 .Procedure