add discriminator (#10451)

Author: changlong-liu

specification/azure-kusto/resource-manager/Microsoft.Kusto/stable/2020-06-14/examples/KustoDatabasesCreateOrUpdate.json

@@ -7,6 +7,7 @@
     "api-version": "2020-06-14",
     "parameters": {
       "location": "westus",
+      "kind": "ReadWrite",
       "properties": {
         "softDeletePeriod": "P1D"
       }