docs/zh_CN/damon: update outdated term 'regions update interval'

Since 072fd1b47215("Docs/damon: update outdated term 'regions update interval'")
use update interval,zh_CN should use 更新间隔, so let's sync update.

Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>