Document Cosmos changes in 9.0

Closes #4808
Part of #4805 (new function translations for Cosmos)

Author: roji

.openpublishing.redirection.json

@@ -479,6 +479,11 @@
             "source_path": "entity-framework/core/logging-events-diagnostics/event-counters.md",
             "redirect_url": "/ef/core/logging-events-diagnostics/metrics",
             "redirect_document_id": false
+        },
+        {
+            "source_path": "entity-framework/core/providers/cosmos/functions.md",
+            "redirect_url": "/ef/core/providers/cosmos/querying",
+            "redirect_document_id": false
         }
     ]
 }