discv5: fix in in

Author: fjl

discv5/discv5-theory.md

@@ -411,7 +411,7 @@ The Relay sends a [RELAYMSG] notification containing Alice's message nonce and E
 
 Bob disassembles the [RELAYMSG] and uses the `nonce` to assemble a [WHOAREYOU packet],
 then sends it to Alice. Bob knows about Alice's endpoint from the `initiator-enr` given in
-in RELAYMSG.
+RELAYMSG.
 
 Bob's NAT adds the mapping `(Bob's-LAN-ip, Bob's-LAN-port, Alice's-WAN-ip,
 Alice's-WAN-port, entry-lifetime)`. A hole is punched in Bob's NAT for Alice for the