docs/zh_CN: Add staging/index Chinese translation

Translate the following files into Chinese:

- Documentation/staging/index.rst

Add it into the menu of zh_CN/index. Also fix one translation
in the zh_CN/index file.
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Rui Li <me@lirui.org>
Link: https://lore.kernel.org/r/896caff38814b7c383324966c3936e8a0bfb1d2e.1666328379.git.me@lirui.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/translations/zh_CN/index.rst

@@ -124,13 +124,13 @@ TODOList:
 其他文档
 --------
 
-有几份未排序的文档似乎不适合放在文档的其他部分，或者可能需要进行一些调整和/或
+有几份未分类的文档似乎不适合放在文档的其他部分，或者可能需要进行一些调整和/或
 转换为reStructureText格式，也有可能太旧。
 
-TODOList:
-
-* staging/index
+.. toctree::
+   :maxdepth: 2
 
+   staging/index
 
 索引和表格
 ----------

Documentation/translations/zh_CN/staging/index.rst

+.. SPDX-License-Identifier: GPL-2.0
+.. include:: ../disclaimer-zh_CN.rst
+
+:Original: Documentation/staging/index.rst
+
+:翻译:
+
+ 李睿 Rui Li <me@lirui.org>
+
+未分类文档
+==========
+
+TODOList:
+
+* crc32
+* lzo
+* remoteproc
+* rpmsg
+* speculation
+* static-keys
+* tee
+* xz