Point all Webpack links to 1.x documentation (#8697)

* Point all Webpack links to 1.x documentation

* Add back webpack production guide, add warning

docs/installation.md

@@ -31,7 +31,7 @@ cd hello-world
 npm start
 ```
 
-Create React App doesn't handle backend logic or databases; it just creates a frontend build pipeline, so you can use it with any backend you want. It uses [webpack](https://webpack.js.org/), [Babel](http://babeljs.io/) and [ESLint](http://eslint.org/) under the hood, but configures them for you.
+Create React App doesn't handle backend logic or databases; it just creates a frontend build pipeline, so you can use it with any backend you want. It uses [webpack](https://webpack.github.io/), [Babel](http://babeljs.io/) and [ESLint](http://eslint.org/) under the hood, but configures them for you.
 
 ## Adding React to an Existing Application
 
@@ -42,7 +42,7 @@ We recommend adding React to a small part of your application, such an individua
 While React [can be used](/react/docs/react-without-es6.html) without a build pipeline, we recommend setting it up so you can be more productive. A modern build pipeline typically consists of:
 
 * A **package manager**, such as [Yarn](https://yarnpkg.com/) or [npm](https://www.npmjs.com/). It lets you take advantage of a vast ecosystem of third-party packages, and easily install or update them.
-* A **bundler**, such as [webpack](https://webpack.js.org/) or [Browserify](http://browserify.org/). It lets you write modular code and bundle it together into small packages to optimize load time.
+* A **bundler**, such as [webpack](https://webpack.github.io/) or [Browserify](http://browserify.org/). It lets you write modular code and bundle it together into small packages to optimize load time.
 * A **compiler** such as [Babel](http://babeljs.io/). It lets you write modern JavaScript code that still works in older browsers.
 
 ### Installing React
@@ -73,7 +73,7 @@ The [Babel setup instructions](https://babeljs.io/docs/setup/) explain how to co
 
 ### Hello World with ES6 and JSX
 
-We recommend using a bundler like [webpack](https://webpack.js.org/) or [Browserify](http://browserify.org/) so you can write modular code and bundle it together into small packages to optimize load time.
+We recommend using a bundler like [webpack](https://webpack.github.io/) or [Browserify](http://browserify.org/) so you can write modular code and bundle it together into small packages to optimize load time.
 
 The smallest React example looks like this:
 
@@ -101,7 +101,11 @@ If you use [Create React App](https://github.com/facebookincubator/create-react-
 
 #### Webpack
 
-Include both `DefinePlugin` and `UglifyJsPlugin` into your production Webpack configuration as described in [this guide](https://webpack.js.org/guides/production-build/).
+-Include both `DefinePlugin` and `UglifyJsPlugin` into your production Webpack configuration as described in [this guide](https://webpack.js.org/guides/production-build/).
+
+> **Note:**
+>
+>This guide works with Webpack 1.x and 2, but is hosted on the new Webpack 2 site. If you're not using the Webpack 2 beta, refer to the [Webpack 1.x website](https://webpack.github.io/) for all other documentation.
 
 #### Browserify