criu --help: add pre-dump to synopsys

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

crtools.c

@@ -350,7 +350,7 @@ int main(int argc, char *argv[])
 usage:
 	pr_msg("\n"
 "Usage:\n"
-"  criu dump -t PID [<options>]\n"
+"  criu dump|pre-dump -t PID [<options>]\n"
 "  criu restore [<options>]\n"
 "  criu show (-D DIR)|(-f FILE) [<options>]\n"
 "  criu check [--ms]\n"