f docs on htlcspendconfirmation

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -404,6 +404,12 @@ enum OnchainEvent {
 		/// commitment transaction, and this is the delay on the to_self output).
 		on_local_output_csv: Option<u16>,
 	},
+	/// A spend of an HTLC output in a commitment transaction, `confirmation_threshold` is is the
+	/// height where a SpendableOutput is generated for local claims or ANTI_REORG_DELAY for
+	/// remote claims.
+	/// Included for both claims and failures, to allow us to track when we should stop informing
+	/// users there is a contentious claim and stop informing users there is a pending claim after
+	/// we generate a `SpendableOutput`.
 	HTLCSpendConfirmation {
 		input_idx: u32,
 		/// Only set if the claim was made by us with a preimage