Update 4.2.1 release notes

(cherry picked from commit fc087ac)

Author: michaelklishin

release-notes/4.2.1.md

@@ -2,10 +2,106 @@
 
 RabbitMQ `4.2.1` is a maintenance release in the `4.2.x` [release series](https://www.rabbitmq.com/release-information).
 
+It is **strongly recommended** that you read [4.2.0 release notes](https://github.com/rabbitmq/rabbitmq-server/releases/tag/v4.2.0)
+in detail if upgrading from a version prior to `4.2.0`.
+
+### Minimum Supported Erlang Version
+
+[RabbitMQ and Erlang/OTP Compatibility Matrix](https://www.rabbitmq.com/docs/which-erlang) has more details on Erlang version requirements for RabbitMQ.
+
+Nodes **will fail to start** on older Erlang releases.
+
+
+## Changes Worth Mentioning
+
+Release notes can be found on GitHub at [rabbitmq-server/release-notes](https://github.com/rabbitmq/rabbitmq-server/tree/v4.2.x/release-notes).
+
 ### Core Server
 
 #### Bug Fixes
 
  * Quorum queue at-most-once dead lettering for the overflow behaviour `drop-head` now happens in the correct order.
 
    GitHub issue: [#14926](https://github.com/rabbitmq/rabbitmq-server/pull/14926)
+
+ * Feature flag state in the registry and on disk were not consistent for a period of time during node boot.
+
+  GitHub issue: [#14943](https://github.com/rabbitmq/rabbitmq-server/pull/14943)
+
+
+### Stream Plugin
+
+#### Bug Fixes
+
+ * `stream.read_ahead` is a new setting that controls how much data is prefetched from disk
+   for stream reads (consumption).
+
+   GitHub issue: [#14948/](https://github.com/rabbitmq/rabbitmq-server/pull/14948)
+
+ * Stream deletion is now more resilient and can handle certain mid-deletion failure scenarios.
+
+   GitHub issue: [#14852](https://github.com/rabbitmq/rabbitmq-server/issues/14852)
+
+
+### Management Plugin
+
+#### Enhancements
+
+ * `GET /api/queues/{vhost}` requests no longer perform unnecessary virtual host permission checks
+   and log less (at `debug` level) as a result.
+
+   GitHub issue: [#14923](https://github.com/rabbitmq/rabbitmq-server/discussions/14923)
+
+
+### Shovel Plugin
+
+#### Bug Fixes
+
+ * Improved target node resource alarm handling for AMQP 1.0 and local shovels.
+
+   GitHub issue: [#14886](https://github.com/rabbitmq/rabbitmq-server/pull/14886)
+
+ * Local shovels could run into an exception that would cause a shovel restart.
+
+   GitHub issue: [#14872](https://github.com/rabbitmq/rabbitmq-server/pull/14872)
+
+
+### OAuth 2 Plugin
+
+#### Bug Fixes
+
+ * A usability improvement allows the plugin to automatically load the trusted system x.509 (TLS) certificates.
+
+   GitHub issue: [#14927](https://github.com/rabbitmq/rabbitmq-server/pull/14927)
+
+
+### LDAP Plugin
+
+#### Bug Fixes
+
+ * A usability improvement allows the plugin to automatically load the trusted system certificates
+   when the user only enables TLS for the LDAP client but does not configure any other settings.
+
+   GitHub issue: [#14937](https://github.com/rabbitmq/rabbitmq-server/pull/14937)
+
+
+### HTTP Auth Backend Plugin
+
+#### Enhancements
+
+ * The HTTP Auth Backend can now optionally provide a custom authorization denial reason to AMQP clients.
+
+   To opt in, return `deny <Reason>` (instead of only `deny`) in the HTTP response body of your HTTP auth backend and set the following in your `rabbitmq.conf` file:
+
+```ini
+auth_http.authorization_failure_disclosure = true
+```
+
+   See the [README](https://github.com/rabbitmq/rabbitmq-server/blob/main/deps/rabbitmq_auth_backend_http/README.md) for more information.
+
+   GitHub issue: [#14641](https://github.com/rabbitmq/rabbitmq-server/pull/14641)
+
+
+### Dependency Changes
+
+ * `cuttlefish` was upgraded to [`3.6.0`](https://github.com/kyorai/cuttlefish/releases)