MAINTAINERS: Add Mailing list and Web-page for PERFORMANCE EVENTS SUBSYSTEM

MAINTAINERS: Add Mailing list and Web-page for PERFORMANCE EVENTS SUBSYSTEM

Add entry "L: linux-perf-users@vger.kernel.org" to archive the
related mail on https://lore.kernel.org/linux-perf-users/, add
entry "W: https://perf.wiki.kernel.org/" so that newbies could
get some useful materials.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/1615780592-21838-1-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>