4.3.0 release notes: add an example

There's likely a reasonable number of environments
that use non-exclusive transient queues, so
let's explicitly provide an example that allows
`deprecated_features.permit.transient_nonexcl_queues`

(cherry picked from commit ed96d65)

Author: michaelklishin

release-notes/4.3.0.md

@@ -27,9 +27,17 @@ by default and require the user to opt-in in order to use them.
 
 This includes [non-durable (transient) non-exclusive](https://www.rabbitmq.com/docs/queues) queues:
 attempts to declare a queue with such property combination will be rejected by default.
-
 Use durable queues or transient exclusive queues instead.
 
+To explicitly allow transient non-exclusive queues, add the following
+line to `rabbitmq.conf`:
+
+```ini
+# Enables deprecated non-durable (transient) non-exclusive queues
+# (disabled by default as of RabbitMQ `4.3.0`, will be removed in a later version)
+deprecated_features.permit.transient_nonexcl_queues = true
+```
+
 ### Classic Queues v1 Storage (CQv1) is Removed
 
 This release removes the original classic queue storage implementation these days
@@ -436,7 +444,7 @@ compared to other versions.
    GitHub issue: [#15730](https://github.com/rabbitmq/rabbitmq-server/pull/15730)
 
  * The deprecated, unused `GET /api/auth` endpoint was removed.
- 
+
    It has been out of use since 3.11 but never removed.
 
    GitHub issue: [#16083](https://github.com/rabbitmq/rabbitmq-server/pull/16083)