docs: Update listener usage

Author: NickLarsenNZ

docs/modules/zookeeper/pages/usage_guide/listenerclass.adoc

@@ -1,15 +1,16 @@
 = Service exposition with ListenerClasses
+:description: Configure the ZooKeeper service exposure with listener classes: cluster-internal, external-unstable or external-stable
 
 Apache ZooKeeper offers an API. The Operator deploys a service called `<name>` (where `<name>` is the name of the ZookeeperCluster) through which ZooKeeper can be reached.
 
-The operator deploys a xref:listener-operator:listener.adoc[Listener] for the Server pod.
+The operator deploys a xref:listener-operator:listener.adoc[Listener] for the Server pods.
 The listener defaults to only being accessible from within the Kubernetes cluster, but this can be changed by setting `.spec.nodes.config.listenerClass`:
 
 [source,yaml]
 ----
 spec:
   servers:
-    config:
+    roleConfig:
       listenerClass: external-unstable  # <1>
 ----
 <1> Specify one of `external-stable`, `external-unstable`, `cluster-internal` (the default setting is `cluster-internal`).