fix license

licenses.json

@@ -26,7 +26,8 @@
   {
     "id": "http://dcat-ap.de/def/licenses/cc-zero",
     "title": "Creative Commons CC Zero License (cc-zero)",
-    "url": "http://www.opendefinition.org/licenses/cc-zero"
+    "url": "http://www.opendefinition.org/licenses/cc-zero",
+    "od_conformance":"approved" 
   },
   {
     "id": "http://dcat-ap.de/def/licenses/cc-by/4.0",