docs/zh_CN: add peci subsystem translation

Translate .../peci/peci.rst into Chinese.

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/00577790cb16375e0016513e03d06b671006a3da.1646108017.git.siyanteng@loongson.cn


Signed-off-by: Jonathan Corbet <corbet@lwn.net>