docs: add release notes entry

Author: ellemouton

docs/release-notes/release-notes-0.19.0.md

@@ -251,6 +251,10 @@ The underlying functionality between those two options remain the same.
   [GoroutineManager](https://github.com/lightningnetwork/lnd/pull/9141) so that 
   its constructor does not take a context.
 
+* [Update protofsm 
+ StateMachine](https://github.com/lightningnetwork/lnd/pull/9342) to use the 
+  new GoroutineManager API along with structured logging.
+
 ## Tooling and Documentation
 
 * [Improved `lncli create` command help text](https://github.com/lightningnetwork/lnd/pull/9077)