Adds nodeport limitation to UDN docs

Author: Steven Smith

modules/nw-udn-limitations.adoc

@@ -24,4 +24,6 @@ While user-defined networks (UDN) offer highly customizable network configuratio
 
 * *Creation and modification limitation*: The `ClusterUserDefinedNetwork` CR and the `UserDefinedNetwork` CR cannot be modified after being created.
 
-* *Default network service access*: A user-defined network pod is isolated from the default network, which means that most default network services are inaccessible. For example, a user-defined network pod cannot currently access the {product-title} image registry. Because of this limitation, source-to-image builds do not work in a user-defined network namespace. Additionally, other functions do not work, including functions to create applications based on the source code in a Git repository, such as `oc new-app <command>`, and functions to create applications from an {product-title} template that use source-to-image builds. This limitation might also affect other `openshift-*.svc` services.
+* *Default network service access*: A user-defined network pod is isolated from the default network, which means that most default network services are inaccessible. For example, a user-defined network pod cannot currently access the {product-title} image registry. Because of this limitation, source-to-image builds do not work in a user-defined network namespace. Additionally, other functions do not work, including functions to create applications based on the source code in a Git repository, such as `oc new-app <command>`, and functions to create applications from an {product-title} template that use source-to-image builds. This limitation might also affect other `openshift-*.svc` services.
+
+* *Connectivity limitation*: NodePort services on user-defined networks are not guaranteed isolation. For example, NodePort traffic from a pod to a service on the same node is not accessible, whereas traffic from a pod on a different node succeeds.