text: Fix footnote tag

Author: real-or-random

README.md

@@ -631,7 +631,7 @@ If a participant deems a protocol session successful (as defined in [Inputs and
 The following figure shows an example ChillDKG involving the participants and the coordinator.
 For simplicity, only one participant is depicted.
 Arrows indicate network messages between the parties.
-Each message sent by the coordinator is a broadcast message[^no-reliable broadcast],
+Each message sent by the coordinator is a broadcast message[^no-reliable-broadcast],
 i.e., the coordinator sends the same message to each participant.
 Unless participants abort due to errors, all participants run the same code and send messages in the same steps.