Add standard badge

Author: kevinsawicki

README.md

@@ -1,6 +1,7 @@
 # <img src="https://cloud.githubusercontent.com/assets/378023/15172388/b2b81950-1790-11e6-9a7c-ccc39912bb3a.png" width="60px" align="center" alt="Electron API Demos icon"> Electron API Demos
 
 [![Build Status](https://travis-ci.org/electron/electron-api-demos.svg?branch=master)](https://travis-ci.org/electron/electron-api-demos)
+[![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat)](http://standardjs.com/)
 
 This is a desktop app that interactively and with sample code demonstrates core features of the [Electron](http://electron.atom.io) API. It's built with Electron, too, of course. This app works on Windows, OS X and Linux operating systems.