docs/release-notes: add release notes

Author: Roasbeef

docs/release-notes/release-notes-0.21.0.md

@@ -69,6 +69,13 @@
 # Improvements
 ## Functional Updates
 
+* [Added panic recovery](https://github.com/lightningnetwork/lnd/pull/10470) to
+  the gossiper's message processing goroutines. This increases the robustness
+  of the gossiper subsystem by allowing it to continue operating even if a
+  logic error causes a panic during message processing. The recovery mechanism
+  ensures dependencies are properly freed and logs the panic trace for
+  debugging.
+
 * [Added support](https://github.com/lightningnetwork/lnd/pull/9432) for the
   `upfront-shutdown-address` configuration in `lnd.conf`, allowing users to
   specify an address for cooperative channel closures where funds will be sent.