message: Add a link to the Add Custom Properties article
diff: @@ -515,6 +515,8 @@ export class QuestionSelectBase extends Question {
  * }
  * ```
  *
  + * Refer to the following help topic for information on how to add custom properties so that they are serialized into JSON: [Add Custom Properties to Property Grid](https://surveyjs.io/survey-creator/documentation/property-grid#add-custom-properties-to-the-property-grid).
  + *
  * If you need to specify only the `value` property, you can set the `choices` property to an array of primitive values, for example, `[ "item1", "item2", "item3" ]`. These values are both saved in survey results and used as display text.
  * @see choicesByUrl
  * @see choicesFromQuestion
  