OSDOCS-14323: updates day 2 operation limitation

Author: JoeAldinger

modules/nw-udn-limitations.adoc

@@ -11,7 +11,7 @@ While user-defined networks (UDN) offer highly customizable network configuratio
 //Check on the removal of the DNS limitation for 4.18 or 4.17.z.
 * *DNS limitations*:
 ** DNS lookups for pods resolve to the pod's IP address on the cluster default network. Even if a pod is part of a user-defined network, DNS lookups will not resolve to the pod's IP address on that user-defined network. However, DNS lookups for services and external entities will function as expected.
-** When a pod is assigned to a primary UDN, it can access the Kubernetes API (KAPI) and DNS services on the cluster's default network. 
+** When a pod is assigned to a primary UDN, it can access the Kubernetes API (KAPI) and DNS services on the cluster's default network.
 
 * *Initial network assignment*: You must create the namespace and network before creating pods. Assigning a namespace with pods to a new network or creating a UDN in an existing namespace will not be accepted by OVN-Kubernetes.
 
@@ -20,4 +20,6 @@ While user-defined networks (UDN) offer highly customizable network configuratio
 
 * *Health check limitations*: Kubelet health checks are performed by the cluster default network, which does not confirm the network connectivity of the primary interface on the pod. Consequently, scenarios where a pod appears healthy by the default network, but has broken connectivity on the primary interface, are possible with user-defined networks.
 
-* *Network policy limitations*: Network policies that enable traffic between namespaces connected to different user-defined primary networks are not effective. These traffic policies do not take effect because there is no connectivity between these isolated networks.
+* *Network policy limitations*: Network policies that enable traffic between namespaces connected to different user-defined primary networks are not effective. These traffic policies do not take effect because there is no connectivity between these isolated networks.
+
+* *Creation and modification limitation*: The `ClusterUserDefinedNetwork` CR and the `UserDefinedNetwork` CR cannot be modified after being created.