chore(docs): add webpack update instructions

Author: filipesilva

README.md

@@ -16,6 +16,12 @@ This project is very much still a work in progress.
 The CLI is now in beta. 
 If you wish to collaborate while the project is still young, check out [our issue list](https://github.com/angular/angular-cli/issues).
 
+## Webpack preview release update
+
+We're updating the build system in Angular-CLI to use webpack instead of Broccoli.
+
+You can install and update your projects using [these instructions](https://github.com/angular/angular-cli/blob/master/WEBPACK_UPDATE.md).
+
 ## Prerequisites
 
 The generated project has dependencies that require 

WEBPACK_UPDATE.md

@@ -0,0 +1,50 @@
+# Upgrading from [email protected] to the angular-cli@webpack 
+
+To update `angular-cli` to the webpack preview, you must update both the global package, project's local package and your project files.
+
+## Global package:
+```
+npm uninstall -g angular-cli
+npm cache clean
+npm install -g angular-cli@webpack
+```
+
+## Local project package:
+```
+rm -rf node_modules dist tmp typings
+npm install --save-dev angular-cli@webpack
+```
+
+## Project files
+
+You will need to run `ng init` to check for changes in all the auto-generated files created by `ng new` and allow you to update yours. You are offered four choices for each changed file: `y` (overwrite), `n` (don't overwrite), `d` (show diff between your file and the updated file) and `h` (help).
+
+Carefully read the diffs for each code file, and either accept the changes or incorporate them manually after `ng init` finishes.
+
+You can find a sample github diff of the changes introduced between a beta.10 and webpack preview project at https://github.com/filipesilva/angular-cli-webpack-upgrade/commit/HEAD.
+
+Here is a summary of the file changes:
+
+1. Updated files:
+  * `./config/karma.conf.js` - `frameworks`/`plugins`/`files`/`exclude`/`preprocessors` entries changed, added `angularCliConfig` entry.
+  * `./e2e/tsconfig.json` - property cleanup, changed `outdir`, added `typeRoots`
+  * `./package.json` - removed typings postinstall script, removed `ember-cli-inject-live-reload`/`es6-shim`/`systemjs` dependencies, added `core-js`/`ts-helpers` dependencies, updated `angular-cli`/`codelyzer`/`ts-node`/`ts-lint`/`typescript` devDependencies, added `@types/jasmine`/`@types/protractor`/`karma-coverage` devDependencies.
+  * `./src/app/app.component.ts` (and all other components) - removed `module.id`.
+  * `./src/app/index.ts` - import adjusted due to environment files moving (see below).
+  * `./src/index.html` - removed templating tags and `SystemJS` import script.
+  * `./src/app/tsconfig.json` - property cleanup, changed `outdir`/`module`, added `libs`/`typeRoots`/`types`
+  * `./src/typings.d.ts` - added `System`/`require` typings, removed `typings` ref 
+  * `./typings.json` - updated `jasmine` globalDevDependency, removed `es6-shim` globalDependency
+1. New files:
+  * `./src/polyfills.ts` - loads needed polyfills before main app
+  * `./src/test.ts` - unit test spec loader
+1. These files have moved to `./src/app/environments/`:
+  * `./config/environment.dev.ts`
+  * `./config/environment.prod.ts`
+  * `./src/app/environment.ts`
+
+Lastly, you can delete these files as they are not needed anymore.
+  * `./config/karma-test-shim.js`
+  * `./src/app/system-config.ts`
+  * `./src/app/typings.d.ts`
+  * `./angular-cli-build.js`