docs/zh_CN: Add mutex-design Chinese translation

Translate locking/mutex-design.rst into Chinese.

Signed-off-by: Tang Yizhou <yizhou.tang@shopee.com>
Reviewed-by: Alex Shi <alexs@kernel.org>
Reviewed-by: Yanteng Si<siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20220629013240.65386-3-yizhou.tang@shopee.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>