docs: add experimental endorsement

Author: carlaKC

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

@@ -37,6 +37,12 @@
   containing blinded paths.
 
 # New Features
+
+* [Support](https://github.com/lightningnetwork/lnd/pull/8390) for 
+  [experimental endorsement](https://github.com/lightning/blips/pull/27) 
+  signal relay was added. This signal has *no impact* on routing, and
+  is deployed experimentally to assist ongoing channel jamming research.
+
 ## Functional Enhancements
 ## RPC Additions
 
@@ -100,6 +106,7 @@
 # Contributors (Alphabetical Order)
 
 * Boris Nagaev
+* Carla Kirk-Cohen
 * CharlieZKSmith
 * Elle Mouton
 * Pins