add Gitpod link and its config file

.gitpod.yml

@@ -0,0 +1,2 @@
+image: gitpod/workspace-full
+

DOCUMENTATION/content/contributing/index.md

@@ -4,6 +4,8 @@ type: index
 weight: 6
 ---
 
+[![Open in Gitpod](https://gitpod.io/button/open-in-gitpod.svg)](https://gitpod.io/#https://github.com/laradock/laradock)
+
 
 ## Have a Question