Modify FeedbackReceiverDto, mark fields with Required

Retroactiune.WebAPI/Models/FeedbackReceiverDto.cs

@@ -1,12 +1,16 @@
-namespace Retroactiune.Models
+using System.ComponentModel.DataAnnotations;
+
+namespace Retroactiune.Models
 {
     /// <summary>
     /// FeedbackReceiverDto is the DTO for <see cref="FeedbackReceiver"/>
     /// </summary>
     public class FeedbackReceiverDto
     {
+        [Required]
         public string Name { get; set; }
 
+        [Required]
         public string Description { get; set; }
     }
 }