docs(readme): add Greenkeeper badge

Author: greenkeeper[bot]

README.md

@@ -8,6 +8,6 @@
 [![DevDependencies Status](https://david-dm.org/basics/code-snippet-to-svg/dev-status.svg)](https://david-dm.org/basics/code-snippet-to-svg?type=dev)
 
 [![start with why](https://img.shields.io/badge/start%20with-why%3F-brightgreen.svg?style=flat)](http://www.ted.com/talks/simon_sinek_how_great_leaders_inspire_action)
-[![JavaScript Style Guide: Good Parts](https://img.shields.io/badge/code%20style-goodparts-brightgreen.svg?style=flat)](https://github.com/dwyl/goodparts "JavaScript The Good Parts")
+[![JavaScript Style Guide: Good Parts](https://img.shields.io/badge/code%20style-goodparts-brightgreen.svg?style=flat)](https://github.com/dwyl/goodparts "JavaScript The Good Parts") [![Greenkeeper badge](https://badges.greenkeeper.io/basics/code-snippet-to-svg.svg)](https://greenkeeper.io/)
 
 # Code snippet to SVG converter