docs/zh_CN add PCI pci.rst translation

Translate ../PCI/pci.rst into Chinese
Signed-off-by: NYanteng Si <siyanteng@loongson.cn>
Reviewed-by: NAlex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/3f871a60421d4079421b4184fdeb789d92a5ea11.1635248253.git.siyanteng@loongson.cnSigned-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/PCI/index.rst

@@ -21,9 +21,10 @@ Linux PCI总线子系统
    :maxdepth: 2
    :numbered:
 
+   pci
+
 Todolist:
 
-   pci
    pciebus-howto
    pci-iov-howto
    msi-howto