docs: add release notes.

Signed-off-by: Nishant Bansal <[email protected]>

Author: NishantBansal2003

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

@@ -121,6 +121,11 @@
   tests to set a lower value for faster funding confirmation timeout while
   keeping the default of 2016 blocks for production stability.
 
+* [Add](https://github.com/lightningnetwork/lnd/pull/9603) validation to ensure
+  that MPP parameters are compatible with the payment amount before attempting
+  the payment. This prevents payments from entering a path finding loop that
+  would eventually timeout.
+
 ## RPC Additions
 
 * [Add a new rpc endpoint](https://github.com/lightningnetwork/lnd/pull/8843)