f update interception docs

Author: valentinewallace

lightning/src/events/mod.rs

@@ -623,6 +623,7 @@ pub enum Event {
 		inbound_amount_msat: u64,
 		/// How many msats the payer intended to route to the next node. Depending on the reason you are
 		/// intercepting this payment, you might take a fee by forwarding less than this amount.
+		/// Forwarding less than this amount may break compatibility with LDK versions prior to 0.0.116.
 		///
 		/// Note that LDK will NOT check that expected fees were factored into this value. You MUST
 		/// check that whatever fee you want has been included here or subtract it as required. Further,

lightning/src/ln/channelmanager.rs

@@ -3485,13 +3485,16 @@ where
 	/// [`ChannelManager::fail_intercepted_htlc`] MUST be called in response to the event.
 	///
 	/// Note that LDK does not enforce fee requirements in `amt_to_forward_msat`, and will not stop
-	/// you from forwarding more than you received.
+	/// you from forwarding more than you received. See
+	/// [`HTLCIntercepted::expected_outbound_amount_msat`] for more on forwarding a different amount
+	/// than expected.
 	///
 	/// Errors if the event was not handled in time, in which case the HTLC was automatically failed
 	/// backwards.
 	///
 	/// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
 	/// [`HTLCIntercepted`]: events::Event::HTLCIntercepted
+	/// [`HTLCIntercepted::expected_outbound_amount_msat`]: events::Event::HTLCIntercepted::expected_outbound_amount_msat
 	// TODO: when we move to deciding the best outbound channel at forward time, only take
 	// `next_node_id` and not `next_hop_channel_id`
 	pub fn forward_intercepted_htlc(&self, intercept_id: InterceptId, next_hop_channel_id: &[u8; 32], next_node_id: PublicKey, amt_to_forward_msat: u64) -> Result<(), APIError> {