Fix broken RGS doc link

Author: tnull

lightning-rapid-gossip-sync/src/lib.rs

@@ -36,7 +36,8 @@
 //!
 //! After the gossip data snapshot has been downloaded, one of the client's graph processing
 //! functions needs to be called. In this example, we process the update by reading its contents
-//! from disk, which we do by calling [`RapidGossipSync::update_network_graph`]:
+//! from disk, which we do by calling `RapidGossipSync::update_network_graph` or
+//! `RapidGossipSync::update_network_graph_no_std`:
 //!
 //! ```
 //! use bitcoin::constants::genesis_block;