docs/zh_CN add PCI pci.rst translation

Translate ../PCI/pci.rst into Chinese

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/3f871a60421d4079421b4184fdeb789d92a5ea11.1635248253.git.siyanteng@loongson.cn


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