docs(cn): add Thinking in React translations (reactjs#8)

* docs(cn): add `Thinking in React` translations

* docs(cn): add translation for `mock`

* docs(cn): modify phrasing in regard to review suggestions

* docs(cn): changes regarding review feedback

* docs(cn): rephrase some words & remove control characters

* docs(cn): revert Wikipedia links to English version

* docs(cn): changes for overall smoothness

Author: robertying