Merge pull request #4438 from rabbitmq/mqtt_quorum_config

Update rabbitmq.conf.example to mention QQ support for MQTT

Author: michaelklishin

deps/rabbit/docs/rabbitmq.conf.example

@@ -883,6 +883,20 @@
 ##
 # mqtt.prefetch = 10
 
+## Sets the durable queue type to be used for QoS 1 subscriptions.
+##
+## Supported types are:
+## 
+## * classic
+## * quorum
+##
+## IMPORTANT: changing this setting requires all existing queues used by
+## the MQTT plugin to be DELETED or clients will fail to subscribe.
+## So this setting should be used for new clusters.
+##
+# mqtt.durable_queue_type = classic
+
+
 
 ## ----------------------------------------------------------------------------
 ## RabbitMQ AMQP 1.0 Support