Set "compatibility" to 1.1

Author: James McKinney

extension.json

@@ -5,10 +5,10 @@
   "description": {
     "en": "Documents at the milestone level were deprecated in OCDS 1.1. This extension re-introduces the ability to attach documents to each individual milestone."
   },
-  "compatibility": [
-    "1.1"
-  ],
   "documentationUrl": {
     "en": "http://standard.open-contracting.org/1.1/en/extensions/milestone_documents/"
-  }
+  },
+  "compatibility": [
+    "1.1"
+  ]
 }