3.12.0 release notes updates

(cherry picked from commit 6b6ee33)

Author: michaelklishin

release-notes/3.12.0.md

@@ -84,24 +84,17 @@ across all architectures, and the most recent TLS 1.3 implementation available t
 Client libraries that were compatible with RabbitMQ `3.11.x` will be compatible with `3.12.0`.
 
 
-
 ### Getting Help
 
 Any questions about this release, upgrades or RabbitMQ in general are welcome on the [RabbitMQ mailing list](https://groups.google.com/forum/#!forum/rabbitmq-users).
 
 
-
 ## Changes Worth Mentioning
 
 Release notes are kept under [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v3.11.x/release-notes).
 
 ### Core Server
 
-#### Bug Fixes
-
-All bug fixes worth mentioning in this release have also shipped
-in the `3.11.x` release series.
-
 #### Enhancements
 
  * Quorum queues now sustain higher throughput with large backlogs. They also offer higher throughput
@@ -178,15 +171,30 @@ in the `3.11.x` release series.
    rabbitmqctl set_policy at-least-once-dead-lettering ".*" '{"dead-letter-strategy": "at-least-once"}' --apply-to quorum_queues
    ```
 
+ * Nodes with a lot of (non-mirrored) classic queues with v2 storage enabled
+   by default (using `classic_queue.default_version = 2`) now boot faster.
+
+   GitHub issue: [#7676](https://github.com/rabbitmq/rabbitmq-server/pull/7676)
+
  * Quorum queues: The `x-delivery-count` header will no longer be added to messages the first time they are delivered (`x-delivery-count=0`)
-   as it has a potential performance impact on consumer deliveries. The documentation already states that the header is only present
-   for re-deliveries.
+   as it has a potential performance impact on consumer deliveries.
 
    GitHub issue: [#7732](https://github.com/rabbitmq/rabbitmq-server/pull/7732)
 
+#### Bug Fixes
+
+This release includes all bug fixes shipped in the `3.11.x` series.
+
+ * Classic mirrored queues that had a [length limit]() defined on them
+   handled the overflow of messages differently from the current elected leader,
+   eventually causing exceptions and replica restarts.
+
+   GitHub issue: [#7579](https://github.com/rabbitmq/rabbitmq-server/pull/7579)
+
+
 ### CLI Tools
 
-#### Features
+#### Enhancements
 
  * `rabbitmq-queues rebalance` now supports streams in addition to classic and quorum queues.
 
@@ -210,6 +218,7 @@ in the `3.11.x` release series.
 
    GitHub issue: [#7135](https://github.com/rabbitmq/rabbitmq-server/pull/7135)
 
+
 ### MQTT Plugin
 
 #### Enhancements
@@ -221,6 +230,7 @@ in the `3.11.x` release series.
 
  * The `x-mqtt-dup` header will no longer be present for consumer deliveries as it wasn't used correctly.
 
+
 ### Management Plugin
 
 #### Enhancements