message: add max bound for application gateway autoscale config
diff: "ApplicationGatewayAutoscaleConfiguration": {
  "properties": {
  "minCapacity": {
  + "type": "integer",
  + "format": "int32",
  + "minimum": 0,
  + "exclusiveMinimum": false,
  + "description": "Lower bound on number of Application Gateway capacity"
  + },
  + "maxCapacity": {
  "type": "integer",
  "format": "int32",
  "minimum": 2,
  "exclusiveMinimum": false,
  - "description": "Lower bound on number of Application Gateway instances"
  + "description": "Upper bound on number of Application Gateway capacity"
  }
  },
  "required": [
  