perf list: Document -v option deduplication feature

-v disables deduplication of similarly suffixed PMUs so add it to the
help and doc strings.

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250226104111.564443-4-james.clark@linaro.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

tools/perf/Documentation/perf-list.txt

@@ -27,7 +27,7 @@ Don't print descriptions.
 
 -v::
 --long-desc::
-Print longer event descriptions.
+Print longer event descriptions and all similar PMUs with alphanumeric suffixes.
 
 --debug::
 Enable debugging output.

tools/perf/builtin-list.c

@@ -527,7 +527,7 @@ int cmd_list(int argc, const char **argv)
 		OPT_BOOLEAN('d', "desc", &default_ps.desc,
 			    "Print extra event descriptions. --no-desc to not print."),
 		OPT_BOOLEAN('v', "long-desc", &default_ps.long_desc,
-			    "Print longer event descriptions."),
+			    "Print longer event descriptions and all similar PMUs with alphanumeric suffixes."),
 		OPT_BOOLEAN(0, "details", &default_ps.detailed,
 			    "Print information on the perf event names and expressions used internally by events."),
 		OPT_STRING('o', "output", &output_path, "file", "output file name"),