f missing docs

Author: TheBlueMatt

lightning/src/ln/channelmanager.rs

@@ -562,10 +562,16 @@ impl_writeable_tlv_based_enum!(EventCompletionAction,
 );
 
 #[derive(Clone, PartialEq, Eq, Debug)]
+/// If something is blocked on the completion of an RAA-generated [`ChannelMonitorUpdate`] we track
+/// the blocked action here. See enum variants for more info.
 pub(crate) enum RAAMonitorUpdateBlockingAction {
-	/// The inbound channel's channel_id
+	/// A forwarded payment was claimed. We block the downstream channel completing its monitor
+	/// update which removes the HTLC preimage until the upstream channel has gotten the preimage
+	/// durably to disk.
 	ForwardedPaymentOtherChannelClaim {
+		/// The upstream channel ID (i.e. the inbound edge).
 		channel_id: [u8; 32],
+		/// The HTLC ID on the inbound edge.
 		htlc_id: u64,
 	},
 }