docs: add release notes for remote graph support

Author: ellemouton

docs/release-notes/release-notes-0.21.0.md

@@ -74,6 +74,16 @@
   non-wumbo channel size (~0.168 BTC), with wumbo channels always requiring
   6 confirmations.
 
+* [Added support for using a remote LND node as a graph data
+  source](https://github.com/lightningnetwork/lnd/pull/9265). This allows a
+  lightweight or mobile node to delegate graph queries to a trusted remote LND
+  node instead of syncing and storing the full network graph locally. The feature
+  introduces a new `GraphSource` interface, a `Mux` that combines local and
+  remote graph data, and an RPC client that connects to the remote node's gRPC
+  API. The local graph cache is kept in sync via a topology subscription. Enable
+  with `--remotegraph.enable` along with `--gossip.no-sync` to disable local
+  gossip syncing.
+
 ## RPC Additions
 
 * The `WaitingCloseChannel` response in `PendingChannels` now includes two

graph/db/graph_source.go

@@ -18,6 +18,8 @@ import (
 // etc.) to work with a unified view of the network without caring about gossip
 // protocol versions or whether the data comes from a local database or a
 // remote source.
+//
+//nolint:interfacebloat
 type GraphSource interface {
 	NodeTraverser