docs: update release notes

Author: ellemouton

docs/release-notes/release-notes-0.18.3.md

@@ -89,6 +89,9 @@
   channel. We will still wait for the channel to have at least one confirmation
   and so the main change here is that we don't error out for such a case.
 
+* [Groundwork](https://github.com/lightningnetwork/lnd/pull/8752) in preparation
+  for implementing route blinding receives.
+
 ## Testing
 ## Database