docs: update deprecated message

Author: mamoonraja

Scripts/Services/NaturalLanguageUnderstanding/V1/Model/CategoriesOptions.cs

@@ -41,8 +41,12 @@ public class CategoriesOptions
         /// Enter a [custom
         /// model](https://cloud.ibm.com/docs/services/natural-language-understanding?topic=natural-language-understanding-customizing)
         /// ID to override the standard categories model
-        /// **Deprecated** the model parameter is no longer supported by the Natural Language Understanding service and will
-        /// be removed in the next major release
+        ///
+        /// **Deprecated**
+        // The custom categories experimental feature will be retired on 19 December 2019. On that date, deployed custom
+        // categories models will no longer be accessible in Natural Language Understanding. The feature will be removed from
+        // Knowledge Studio on an earlier date. Custom categories models will no longer be accessible in Knowledge Studio on 17
+        // December 2019.
         /// </summary>
         [JsonProperty("model", NullValueHandling = NullValueHandling.Ignore)]
         public string Model { get; set; }