Update webpack links to point to webpack 2 (facebook#2492)

* Update README.md to make links to webpack point to webpack.js.org instead
  insteade of webpack 1 webpack.githup.io

README.md

@@ -199,7 +199,7 @@ Some of them might get added in the future if they are stable, are useful to maj
 The tools used by Create React App are subject to change.
 Currently it is a thin layer on top of many amazing community projects, such as:
 
-* [webpack](https://webpack.github.io/) with [webpack-dev-server](https://github.com/webpack/webpack-dev-server), [html-webpack-plugin](https://github.com/ampedandwired/html-webpack-plugin) and [style-loader](https://github.com/webpack/style-loader)
+* [webpack](https://webpack.js.org/) with [webpack-dev-server](https://github.com/webpack/webpack-dev-server), [html-webpack-plugin](https://github.com/ampedandwired/html-webpack-plugin) and [style-loader](https://github.com/webpack/style-loader)
 * [Babel](http://babeljs.io/) with ES6 and extensions used by Facebook (JSX, [object spread](https://github.com/sebmarkbage/ecmascript-rest-spread/commits/master), [class properties](https://github.com/jeffmo/es-class-public-fields))
 * [Autoprefixer](https://github.com/postcss/autoprefixer)
 * [ESLint](http://eslint.org/)
@@ -248,5 +248,5 @@ Notable alternatives also include:
 * [dev-toolkit](https://github.com/stoikerty/dev-toolkit)
 * [sku](https://github.com/seek-oss/sku)
 
-You can also use module bundlers like [webpack](http://webpack.github.io) and [Browserify](http://browserify.org/) directly.<br>
+You can also use module bundlers like [webpack](http://webpack.js.org) and [Browserify](http://browserify.org/) directly.<br>
 React documentation includes [a walkthrough](https://facebook.github.io/react/docs/package-management.html) on this topic.