message: Add app sku as part of update request
diff: "type": "string"
  }
  },
  + "sku": {
  + "description": "A valid instance SKU.",
  + "$ref": "#/definitions/AppSkuInfo"
  + },
  "properties": {
  "description": "The common properties of an IoT Central application.",
  "x-ms-client-flatten": true,
  