docs/zh_CN: add admin-guide damon index translation

Translate .../admin-guide/mm/damon/index.rst into Chinese.

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/0251f09dc926972068329b87b0563dd432849497.1646899089.git.siyanteng@loongson.cn


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