doc/zh-CN: Update cpu-freq/core.rst to make it more readable

These Chinese translations are easier to understand.

Also update the first memeber of struct cpufreq_freqs.

Signed-off-by: Tang Yizhou <tangyizhou@huawei.com>
Acked-by: Yanteng Si <siyanteng@loongson.cn>
Reviewed-by: Alex Shi <alexs@kernel.org>
Link: https://lore.kernel.org/r/20211202130240.27942-1-tangyizhou@huawei.com


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