docs/zh_CN: Add how-to of Chinese translation

docs/zh_CN: Add how-to of Chinese translation

Many new faces keep appearing on the mailing list from time to
time, and there may be many potential developers who want to
participate in the Chinese translation but don't know how to
get started. As more and more documents are translated, it is
becoming increasingly important to improve the maintainability
of Chinese documents. We have a lot of conventions, but currently
these conventions are still being passed on orally. At the same
time, during the review process, especially for the first few
patches submitted by newbies, we have made too many repetitive
comments. In order to address the above issues, I have drafted
this guide, and there is still a lot that needs to be improved.

Alex Shi: Fix a embedded code white space issue.
Co-developed-by: Dongliang Mu <dzm91@hust.edu.cn>
Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>
Signed-off-by: Yanteng Si <si.yanteng@linux.dev>
Link: https://lore.kernel.org/r/0443c86e10d900a4d752d103265c948360563d43.1743156287.git.si.yanteng@linux.dev
Signed-off-by: Alex Shi <alexs@kernel.org>