docs(readme): add Greenkeeper badge

greenkeeper[bot] · greenkeeper[bot] · commit f6a1eae3ac0b · 2018-09-17T13:49:36.000Z
diff --git a/README.md b/README.md
@@ -1,3 +1,3 @@
-[![Build Status](https://travis-ci.org/watsonwork/watsonwork-api-proxy.svg?branch=master)](https://travis-ci.org/watsonwork/watsonwork-api-proxy)
+[![Build Status](https://travis-ci.org/watsonwork/watsonwork-api-proxy.svg?branch=master)](https://travis-ci.org/watsonwork/watsonwork-api-proxy) [![Greenkeeper badge](https://badges.greenkeeper.io/watsonwork/watsonwork-api-proxy.svg)](https://greenkeeper.io/)
 
 # watsonwork-api-proxy

Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,3 @@`
`1`		`-[![Build Status](https://travis-ci.org/watsonwork/watsonwork-api-proxy.svg?branch=master)](https://travis-ci.org/watsonwork/watsonwork-api-proxy)`
	`1`	`+[![Build Status](https://travis-ci.org/watsonwork/watsonwork-api-proxy.svg?branch=master)](https://travis-ci.org/watsonwork/watsonwork-api-proxy) [![Greenkeeper badge](https://badges.greenkeeper.io/watsonwork/watsonwork-api-proxy.svg)](https://greenkeeper.io/)`
`2`	`2`
`3`	`3`	`# watsonwork-api-proxy`