docs: add release-notes.

Author: ziggie1984

docs/release-notes/release-notes-0.18.5.md

@@ -0,0 +1,8 @@
+## Bug Fixes
+
+* [Improved user experience](https://github.com/lightningnetwork/lnd/pull/9454)
+ by returning a custom error code when HTLC carries incorrect custom records.
+
+# Contributors (Alphabetical Order)
+
+* Ziggie