book: fix event_action link

doc/src/misc/ircd/specification.md

@@ -4,7 +4,7 @@
 ## PrivMsgEvent
 
 This is the main message type inside Ircd. The `PrivMsgEvent` is an
-[event action](https://darkrenaissance.github.io/darkfi/misc/hashchain/hashchain.html#eventaction).
+[event action](https://darkrenaissance.github.io/darkfi/misc/event_graph/network_protocol.html#event).
 
 
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