Add Greenkeeper badge 🌴 (#21)

greenkeeper[bot] · Arcanemagus · commit 6f77ad14d741 · 2017-12-27T15:37:48.000-08:00
* docs(readme): add Greenkeeper badge
diff --git a/README.md b/README.md
@@ -1,4 +1,7 @@
 # check-peer-deps
+
+[![Greenkeeper badge](https://badges.greenkeeper.io/Arcanemagus/check-peer-deps.svg)](https://greenkeeper.io/)
+
 Verifies that the `peerDependency` requirements of all top level dependencies
 are satisfied.
 
