Add some pictures

Author: gaearon

README.md

@@ -15,6 +15,8 @@ npm start
 
 Then open [http://localhost:3000/](http://localhost:3000/) to see your app.
 
+<img src='https://camo.githubusercontent.com/506a5a0a33aebed2bf0d24d3999af7f582b31808/687474703a2f2f692e696d6775722e636f6d2f616d794e66434e2e706e67' width='600' alt='npm start'>
+
 When you’re ready to deploy to production, create a minified bundle with `npm run build`.
 
 ## Getting Started
@@ -69,7 +71,9 @@ Runs the app in development mode.<br>
 Open [http://localhost:3000](http://localhost:3000) to view it in the browser.
 
 The page will reload if you make edits.<br>
-You will also see any lint errors in the console.
+You will also build errors and lint warnings in the console.
+
+<img src='https://camo.githubusercontent.com/41678b3254cf583d3186c365528553c7ada53c6e/687474703a2f2f692e696d6775722e636f6d2f466e4c566677362e706e67' width='600' alt='Build errors'>
 
 ### `npm run build`