Adding missing comma

Author: stevespringett

about/working-groups/working-groups.json

@@ -158,7 +158,7 @@
     "lastName": "Johansson",
     "headshot": "https://avatars.githubusercontent.com/u/20310?v=4",
     "organization": "Edvina AB",
-    "description": null
+    "description": null,
     "twitter": "oej",
     "linkedin": "ollejohansson",
     "github": "oej",