Updating Examples To Function Components & Hooks

Hi, I am new to react and was just going through the documentation. When, I discovered that most of the examples in the react documentation are outdated, they still use class instead of a function component.

Few Examples Of This :

https://reactjs.org/docs/forms.html
https://reactjs.org/docs/lifting-state-up.html

Also, I believe showing the integration of hooks in these examples, will be of much great help to beginners.

从 docs/forms.html 和 docs/lifting-state-up.html 中的示例开始，然后将它们与当前关于函数组件和 hooks 的文档约定进行比较。更新已确定的示例，使其演示函数组件和 hooks，并验证这两个页面都不再依赖类组件。