Comment about 404/401 for missing (ircd).

ircd_test.go

@@ -113,6 +113,7 @@ var abortAfter int = 150 // Milliseconds to abort part 3
 	SASL authentication testing.
 	TLS support, we make our own certificates.
 	Any messages sent to "echo" are reflected back to the client.
+	Any messages to missing/#missing are returned 404/401.
 */
 func ircServer(listener net.Listener, t *testing.T, config *IRCConfig) {
 	var server net.Conn