docs/zh_TW: add translations for zh_TW/cpu-freq

Create new translations for zh_TW/cpu-freq and link them to index.

Signed-off-by: Hu Haowen <src.res@email.cn>
Link: https://lore.kernel.org/r/20210821094059.64300-2-src.res@email.cn


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