[DOC RHEL] Control Plane Listener configuration for Streams on RHEL

The optional Control Plane Listener can be enabled in the listener configuration [2] for the Kafka broker (in the server.properties file).

control.plane.listener.name

From the Kafka docs: "If not explicitly configured, the default value will be null and there will be no dedicated endpoints for controller connections."

Add some basic information about the control.plane.listener.name option. Do NOT add any information about feature gates.

Release notes are not required.

[1]https://kafka.apache.org/documentation/#brokerconfigs_control.plane.listener.name

[2]https://access.redhat.com/documentation/en-us/red_hat_amq/2021.q2/html/using_amq_streams_on_rhel/configuring_kafka#con-kafka-listener-configuration-str