docs/zh_CN: Add dev-tools/kmemleak Chinese translation

Translate dev-tools/kmemleak.rst into Chinese and add it into
zh_CN/dev-tools/index.rst.

Signed-off-by: Haoyang Liu <tttturtleruss@hust.edu.cn>
Reviewed-by: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240406083643.5056-1-tttturtleruss@hust.edu.cn