perf list: Fix metricgroups title message

  $ perf list metricgroups

gives

  List of pre-defined events (to be used in -e):

  Metric Groups:

  Backend
  Bad
  BadSpec

But that's incorrect of course because metric groups or metrics can only
be specified with -M. So fix the message to say -e or -M
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20221004192634.998984-1-ak@linux.intel.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-list.c

@@ -60,7 +60,7 @@ int cmd_list(int argc, const char **argv)
 	setup_pager();
 
 	if (!raw_dump && pager_in_use())
-		printf("\nList of pre-defined events (to be used in -e):\n\n");
+		printf("\nList of pre-defined events (to be used in -e or -M):\n\n");
 
 	if (hybrid_type) {
 		pmu_name = perf_pmu__hybrid_type_to_pmu(hybrid_type);