docs: add demo

README.md

@@ -5,9 +5,7 @@
 
 > [ExpressJS](http://expressjs.com/) + [Nuxt.js](https://nuxtjs.org) = :zap:
 
-## Live Demo
-
-[https://express.nuxtjs.org](https://express.nuxtjs.org)
+Live Demo: [https://codesandbox.io/s/github/nuxt-community/express-template/tree/demo](https://codesandbox.io/s/github/nuxt-community/express-template/tree/demo)
 
 ## Installation
 
@@ -34,10 +32,6 @@ npm install # or yarn install
 | npm run build | Build the nuxt.js web application for production. |
 | npm start | Start ExpressJS server in production. |
 
-## Backpack
-
-We use [backpack](https://github.com/palmerhq/backpack) to watch and build the application, so you can use the latest ES6 features (module syntax, async/await, etc.).
-
 ## Examples
 
 - [Handling Protected SSR Routes](https://github.com/nuxt/express/blob/master/protected-ssr-api.md)