[9.x] Document withoutTimestamps (laravel#8238)

* document withoutTimestamps

* Update eloquent.md

Co-authored-by: Taylor Otwell <[email protected]>

Author: timacdonald

eloquent.md

@@ -310,6 +310,10 @@ If you need to customize the names of the columns used to store the timestamps,
         const UPDATED_AT = 'updated_date';
     }
 
+If you would like to perform model operations without the model having its `updated_at` timestamp modified, you may operate on the model within a closure given to the `withoutTimestamps` method:
+
+    Model::withoutTimestamps(fn () => $post->incrememt(['reads']));
+
 <a name="database-connections"></a>
 ### Database Connections