Merge pull request #89 from OffchainLabs/clabot

Add clabot config

Author: Tristan-Wilson

.clabot

@@ -0,0 +1,5 @@
+{
+  "contributors": "https://api.github.com/repos/OffchainLabs/clabot-config/contents/nitro-contributors.json",
+  "message": "We require contributors to sign our Contributor License Agreement. In order for us to review and merge your code, please sign the linked documents below to get yourself added. https://na3.docusign.net/Member/PowerFormSigning.aspx?PowerFormId=b15c81cc-b5ea-42a6-9107-3992526f2898&env=na3&acct=6e152afc-6284-44af-a4c1-d8ef291db402&v=2",
+  "label": "s"
+}