Add updating instructions

Fixes #119

Author: gaearon

template/README.md

@@ -3,6 +3,7 @@ You can find the most recent version of this guide [here](https://github.com/fac
 
 ## Table of Contents
 
+- [Updating to New Releases](#updating-to-new-releases)
 - [Sending Feedback](#sending-feedback)
 - [Folder Structure](#folder-structure)
 - [Available Scripts](#available-scripts)
@@ -21,6 +22,23 @@ You can find the most recent version of this guide [here](https://github.com/fac
 - [Deploying](#deploying)
 - [Something Missing?](#something-missing)
 
+## Updating to New Releases
+
+Create React App is divided into two packages:
+
+* `create-react-app` is a global command-line utility that you use to create new projects.
+* `react-scripts` is a development dependency in the generated projects (including this one).
+
+You almost never need to update `create-react-app` itself: it’s delegates all the setup to `react-scripts`.
+
+When you run `create-react-app`, it always creates the project with the latest version of `react-scripts` so you’ll get all the new features and improvements in newly created apps automatically.
+
+To update an existing project to a new version of `react-scripts`, [open the changelog](https://github.com/facebookincubator/create-react-app/blob/master/CHANGELOG.md), find the version you’re currently on (check `package.json` in this folder if you’re not sure), and apply the migration instructions for the newer versions.
+
+In most cases bumping the `react-scripts` version in `package.json` and running `npm install` in this folder should be enough, but it’s good to consult the [changelog](https://github.com/facebookincubator/create-react-app/blob/master/CHANGELOG.md) for potential breaking changes.
+
+We commit to keeping the breaking changes minimal so you can upgrade `react-scripts` painlessly.
+
 ## Sending Feedback
 
 We are always open to [your feedback](https://github.com/facebookincubator/create-react-app/issues).