Remove discord link in README.md (react-toolbox#1593)

The channel doesn't exist anymore

related to react-toolbox#107

Author: bbigras

README.md

@@ -1,6 +1,6 @@
 # <a href='http://react-toolbox.com'><img src='http://i.imgur.com/VCSElQX.png' height='50'></a>
 
-[![npm version](https://img.shields.io/npm/v/react-toolbox.svg?style=flat-square)](https://www.npmjs.com/package/react-toolbox) [![Build Status](http://img.shields.io/travis/react-toolbox/react-toolbox/master.svg?style=flat-square)](https://travis-ci.org/react-toolbox/react-toolbox) [![NPM Status](http://img.shields.io/npm/dm/react-toolbox.svg?style=flat-square)](https://www.npmjs.org/package/react-toolbox) [![react-toolbox channel on discord](https://img.shields.io/badge/discord-%23react--toolbox%20%40%20reactiflux-61dafb.svg?style=flat-square)](https://discord.gg/0ZcbPKXt5bW9FLzM) [![Donate](https://img.shields.io/badge/donate-paypal-blue.svg?style=flat-square)](https://paypal.me/javivelasco) [![OpenCollective](https://opencollective.com/react-toolbox/backers/badge.svg)](#backers) 
+[![npm version](https://img.shields.io/npm/v/react-toolbox.svg?style=flat-square)](https://www.npmjs.com/package/react-toolbox) [![Build Status](http://img.shields.io/travis/react-toolbox/react-toolbox/master.svg?style=flat-square)](https://travis-ci.org/react-toolbox/react-toolbox) [![NPM Status](http://img.shields.io/npm/dm/react-toolbox.svg?style=flat-square)](https://www.npmjs.org/package/react-toolbox) [![Donate](https://img.shields.io/badge/donate-paypal-blue.svg?style=flat-square)](https://paypal.me/javivelasco) [![OpenCollective](https://opencollective.com/react-toolbox/backers/badge.svg)](#backers) 
 [![OpenCollective](https://opencollective.com/react-toolbox/sponsors/badge.svg)](#sponsors)
 
 React Toolbox is a set of [React](http://facebook.github.io/react/) components that implement [Google's Material Design specification](https://material.google.com/). It's powered by [CSS Modules](https://github.com/css-modules/css-modules) and harmoniously integrates with your [webpack](http://webpack.github.io/) workflow, although you can use any other module bundler. You can take a tour through our documentation website and try the components live!