refactor: Avoid variable name pollution

Merge branch 'master' of https://github.com/wll8/redoc-try

feat: Avoid swagger being overwritten by callback functions.

build: Make npm tool convert code to es5

fix: `redocOptions` is not recognized correctly

refactor: 把 css 文件也放在 js 中

doc: 更新示例及文档