minor doc update (#2414)

* Update external-clients.md

Author: Tom Barnes

documentation/staging/content/faq/external-clients.md

@@ -148,6 +148,13 @@ is hosted outside of the Kubernetes cluster, then:
   This can significantly speedup connection creation for EJB and JMS clients.
   See [Configuring WebLogic Server affinity load balancing algorithms](#configuring-weblogic-server-affinity-load-balancing-algorithms).
 
+- __JTA NOTE__: The operator does not directly support external WebLogic JTA access
+  to a Kubernetes hosted WebLogic cluster. This is because external JTA access
+  requires each server in a cluster to be individually addressable,
+  but this conflicts with the current operator requirement that
+  a network channel in a cluster have the same port across all servers in the cluster.
+  If this is a requirement, then contact the WebLogic Kubernetes Operator team for potential solutions.
+
 If a WebLogic EJB or JMS resource is hosted outside of
 a Kubernetes cluster, and the EJB or JMS applications
 that call the resource are located within the cluster, then:
@@ -164,6 +171,11 @@ that call the resource are located within the cluster, then:
     This can significantly speedup tunneling connection creation for EJB and JMS clients.
     See [Configuring WebLogic Server affinity load balancing algorithms](#configuring-weblogic-server-affinity-load-balancing-algorithms).
 
+- __JTA NOTE__: WebLogic does not directly support JTA access to a cluster that is exposed
+  using a single port. This is because external JTA requires each server in a cluster
+  to be individually addressable.
+  If this is a requirement, then contact the WebLogic Kubernetes Operator team for potential solutions.
+
 {{% notice note %}}
 All DNS addresses must be 'DNS-1123' compliant;
 this means that any DNS names created using the name of a service,