missing anchor

10_onion_routing.asciidoc

@@ -800,6 +800,7 @@ Each hop receiving an error, will generate an +ammag+ key and obfuscate the retu
 
 Eventually, the sender (origin node) receives a return packet. It will then generate +ammag+ and +um+ keys for each hop and XOR de-obfuscate the return error iteratively until it reveals the return packet.
 
+[[failure_messages]]
 ==== Failure Messages
 
 The +failuremsg+ is defined in https://github.com/lightningnetwork/lightning-rfc/blob/master/04-onion-routing.md#failure-messages[BOLT #4 - Onion Routing - Failure Messages].
@@ -877,7 +878,7 @@ pre-image (which _must_ match the payment hash of the HTLC) to settle the
 payment. As a result, `keysend` payments can be carried out without first
 obtaining an invoice from the receiver, as the pre-image is "pushed" over to
 the receiver. A `keysend` payment uses a TLV custom record type of `5482373484`
-to encode a 32-byte pre-image value. 
+to encode a 32-byte pre-image value.
 
 ==== Keysend and Custom Records in Lightning Applications