docs: add release note for #10540

Author: morehouse

docs/release-notes/release-notes-0.20.1.md

@@ -82,6 +82,12 @@
   The fix adds automatic format detection to handle both legacy (raw feature
   bits) and new (length-prefixed) formats.
 
+* [Fixed a shutdown
+  deadlock](https://github.com/lightningnetwork/lnd/pull/10540) in the gossiper.
+  Certain gossip messages could cause multiple error messages to be sent on a
+  channel that was only expected to be used for a single message. The erring
+  goroutine would block on the second send, leading to a deadlock at shutdown.
+
 # New Features
 
 ## Functional Enhancements
@@ -152,4 +158,5 @@
 
 * Abdulkbk
 * bitromortac
+* Matt Morehouse
 * Ziggie