docs: update release notes

Author: GeorgeTsagk

docs/release-notes/release-notes-0.18.1.md

@@ -0,0 +1,7 @@
+* Some new experimental [RPCs for managing SCID 
+  aliases](https://github.com/lightningnetwork/lnd/pull/8509) were added under
+  the routerrpc package. These methods allow manually adding and deleting scid 
+  aliases locally to your node.
+  > NOTE: these new RPC methods are marked as experimental 
+        (`XAddLocalChanAliases` & `XDeleteLocalChanAliases`) and upon calling
+        them the aliases will not be communicated with the channel peer.