perf_counter tools: add 'perf help'

Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/Documentation/perf_counter/perf.c b/Documentation/perf_counter/perf.c
index 20d508c..8d6faec 100644
--- a/Documentation/perf_counter/perf.c
+++ b/Documentation/perf_counter/perf.c
@@ -248,6 +248,7 @@
 {
 	const char *cmd = argv[0];
 	static struct cmd_struct commands[] = {
+		{ "help", cmd_help, 0 },
 		{ "record", cmd_record, 0 },
 		{ "stat", cmd_stat, 0 },
 		{ "top", cmd_top, 0 },