MINOR: init: indicate to check 'bind' lines when no listeners were found.

It used to still mention '<listen>'.

src/haproxy.c

@@ -1666,7 +1666,7 @@ int main(int argc, char **argv)
 	}
 
 	if (listeners == 0) {
-		Alert("[%s.main()] No enabled listener found (check the <listen> keywords) ! Exiting.\n", argv[0]);
+		Alert("[%s.main()] No enabled listener found (check for 'bind' directives) ! Exiting.\n", argv[0]);
 		/* Note: we don't have to send anything to the old pids because we
 		 * never stopped them. */
 		exit(1);