f update docs on HTLCUpdate

Author: TheBlueMatt

lightning/src/chain/channelmonitor.rs

@@ -388,9 +388,9 @@ impl OnchainEventEntry {
 /// once they mature to enough confirmations (ANTI_REORG_DELAY)
 #[derive(PartialEq)]
 enum OnchainEvent {
-	/// HTLC output getting solved by a timeout, at maturation we pass upstream payment source information to solve
-	/// inbound HTLC in backward channel. Note, in case of preimage, we pass info to upstream without delay as we can
-	/// only win from it, so it's never an OnchainEvent
+	/// HTLC output being spent by an HTLC-timeout or timeout-condition claim. If an HTLC is
+	/// claimed with a preimage we pass the preimage upstream immediately, so it will only appear
+	/// as an `HTLCSpendConfirmation`, below.
 	HTLCUpdate {
 		source: HTLCSource,
 		payment_hash: PaymentHash,