Swagger correctness fix : add zonal-configuration property (#17447)

Co-authored-by: Priyankar Gupta <priyagupta@microsoft.com>

Author: priyankarking

specification/redis/resource-manager/Microsoft.Cache/stable/2020-12-01/redis.json

@@ -1867,6 +1867,11 @@
               "type": "string",
               "description": "The max clients config",
               "readOnly": true
+            },
+            "zonal-configuration": {
+              "type": "string",
+              "description": "Zonal Configuration",
+              "readOnly": true
             }
           },
           "additionalProperties": {