Didn't mention default behavior of onInternalKeyDown 

It would be better to mention there is a default behavior of [onInternalKeyDown](https://github.com/react-component/switch/blob/master/src/index.tsx#L68) in antd Switch.
https://ant.design/components/switch-cn/#API