docs/zh_CN: add the translation of kbuild/kbuild.rst

docs/zh_CN: add the translation of kbuild/kbuild.rst

Finish the translation of kbuild/kbuild.rst and move kbuild
from TODO to the main body.

Update to commit 2eb5d7f24299 ("kbuild: doc: describe the -C
option precisely for external module builds")

Signed-off-by: Dongliang Mu <dzm91@hust.edu.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241016131710.2619567-1-dzm91@hust.edu.cn