Merge pull request #11 from sandstreamdev/greenkeeper/initial

Add Greenkeeper badge 🌴

Author: jakubbogacz

README.md

@@ -1,5 +1,6 @@
 # std
 
+[![Greenkeeper badge](https://badges.greenkeeper.io/sandstreamdev/std.svg)](https://greenkeeper.io/)
 [![All Contributors](https://img.shields.io/badge/all_contributors-4-orange.svg?style=flat-square)](#contributors)
 
 ## Contributors ✨