docs/zh_CN: add scheduler sched-arch translation

Translate .../scheduler/sched-arch.rst into Chinese.

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/f9e66ba8920bc1bb3f1d67044f64712fa30db7c9.1638517064.git.siyanteng@loongson.cn


Signed-off-by: Jonathan Corbet <corbet@lwn.net>