Set up npm mirror React Native environment construction

After installing node, it is recommended to set up an npm mirror to speed up the subsequent process (or use scientific Internet tools). Note: don't use cnpm! The module path installed by cnpm is strange, and the packager cannot recognize it normally!

npm config set registry https://registry.npm.taobao.org --global
npm config set disturl https://npm.taobao.org/dist --global

React native environment build
https://github.com/reactnativecn/react-native.cn/blob/stable/docs/docs/0.51/getting-started.md