3.12.0 release notes: don't claim that CQv2 is the default version

Author: michaelklishin

release-notes/3.12.0.md

@@ -112,12 +112,12 @@ in the `3.11.x` release series.
  * Reduced memory footprint, improved memory use predictability and throughput of classic queues (version 2, or CQv2).
    This particularly benefits classic queues with longer backlogs.
 
-   Classic queue v2 (CQv2) storage implementation **is now the default**. It is possible to switch
-   the default back to CQv1 using `rabbitmq.conf`:
+   Classic queue v2 (CQv2) storage implementation can be enabled for all classic queues
+   using `rabbitmq.conf`:
 
    ``` ini
-   # uses CQv1 by default
-   classic_queue.default_version = 1
+   # uses CQv2 for all classic queues by default
+   classic_queue.default_version = 2
    ```
 
    GitHub issues: [#4522](https://github.com/rabbitmq/rabbitmq-server/pull/4522), [#7516](https://github.com/rabbitmq/rabbitmq-server/pull/7516)