Update admin.json

Author: adamfowlerit

_data/portals/admin.json

@@ -320,6 +320,10 @@
         "portalName": "Azure AI Content Safety Studio",
         "primaryURL": "https://contentsafety.cognitive.azure.com/"
     },
+    {
+        "portalName": "Azure AI Document Intelligence Studio",
+        "primaryURL": "https://documentintelligence.ai.azure.com/"
+    },
     {
         "portalName": "Azure Machine Learning Studio",
         "primaryURL": "https://ml.azure.com"