event: fix typo (#15270)

event/event.go

@@ -56,7 +56,7 @@ func (mux *TypeMux) Subscribe(types ...interface{}) *TypeMuxSubscription {
 	defer mux.mutex.Unlock()
 	if mux.stopped {
 		// set the status to closed so that calling Unsubscribe after this
-		// call will short curuit
+		// call will short circuit.
 		sub.closed = true
 		close(sub.postC)
 	} else {