docs/zh_CN: add msi-howto translation

Translate .../PCI/msi-howto.rst into Chinese.
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/d62846e2e820f600c27dc5e49887b3a2892eec17.1639224005.git.siyanteng@loongson.cnSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/PCI/index.rst

@@ -24,11 +24,11 @@ Linux PCI总线子系统
    pci
    pciebus-howto
    pci-iov-howto
+   msi-howto
 
-Todolist:
 
+Todolist:
 
-   msi-howto
    sysfs-pci
    acpi-info
    pci-error-recovery