docs/zh_CN: Add coding-style into docs build system

Tested by the command:

make htmldocs

During the compiling process, zh_CN/coding-style.rst has no errors and
warnings generated, the generated html document has been checked.

Signed-off-by: Andy Deng <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>

Documentation/index.rst

···
 from the point of view of a kernel developer.  Much of the information here
 is taken directly from the kernel source, with supplemental material added
 as needed (or at least as we managed to add it — probably *not* all that is
-needed). 
+needed).
 
 .. toctree::
    :maxdepth: 2
···
    :maxdepth: 1
 
    translations/ko_KR/index
+
+Chinese translations
+--------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   translations/zh_CN/index
 
 Indices and tables
 ==================

Documentation/translations/zh_CN/index.rst

···
+.. raw:: latex
+
+	\renewcommand\thesection*
+	\renewcommand\thesubsection*
+
+Chinese translations
+====================
+
+.. toctree::
+   :maxdepth: 1
+
+   coding-style