f - Mention NetworkUpdateHandler in BackgroundProcessor docs

Author: jkczyz

lightning-background-processor/src/lib.rs

@@ -120,7 +120,8 @@ impl BackgroundProcessor {
 	/// # Event Handling
 	///
 	/// `event_handler` is responsible for handling events that users should be notified of (e.g.,
-	/// payment failed). See [`EventHandler`] for details.
+	/// payment failed). See [`EventHandler`] for details. As a convenience, `BackgroundProcessor`
+	/// decorates the user-provided event handler with [`NetworkUpdateHandler`].
 	///
 	/// [top-level documentation]: Self
 	/// [`join`]: Self::join