f add docs

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -6110,6 +6110,10 @@ where
 		self.pending_outbound_payments.clear_pending_payments()
 	}
 
+	/// When something which was blocking a channel from updating its [`ChannelMonitor`] (e.g. an
+	/// [`Event`] being handled) completes, this should be called to restore the channel to normal
+	/// operation. It will double-check that nothing *else* is also blocking the same channel from
+	/// making progress and then any blocked [`ChannelMonitorUpdate`]s fly.
 	fn handle_monitor_update_release(&self, counterparty_node_id: PublicKey, channel_funding_outpoint: OutPoint, mut completed_blocker: Option<RAAMonitorUpdateBlockingAction>) {
 		let mut errors = Vec::new();
 		loop {