docs(readme): add Greenkeeper badge

greenkeeper[bot] · greenkeeper[bot] · commit c18253c77151 · 2017-12-05T17:12:57.000Z
diff --git a/README.md b/README.md
@@ -7,6 +7,8 @@
 
 # Subversion source control for VS Code
 
+[![Greenkeeper badge](https://badges.greenkeeper.io/JohnstonCode/svn-scm.svg)](https://greenkeeper.io/)
+
 # Prerequisites
 
 > **Note**: This extension leverages your machine's SVN installation,\
