adding slack badge and link to autoinvite

Author: etiennemargraff

README.md

@@ -6,6 +6,10 @@ Understand all about Vorlon.js in 20 minutes watching this video : https://chann
 
 Learn more at [VorlonJS](http://vorlonjs.com).
 
+Chat with us on slack (get a free invite clicking on the badge below)
+
+[![Slack Status](https://slackinvorlon.azurewebsites.net/badge.svg)](https://slackinvorlon.azurewebsites.net/)
+
 ## Deploy on Azure  
  [![Deploy to Azure](http://azuredeploy.net/deploybutton.png)](https://azuredeploy.net/)