doc/zh-CN: Update cpufreq-stats.rst to make it more readable

These Chinese translations are easier to understand.
Also add proofreader.

Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Acked-by: Yanteng Si <siyanteng@loongson.cn>
Link: https://lore.kernel.org/r/20211202142312.20052-1-tangyizhou@huawei.com


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