docs: add XML comments for messengers

src/PepperDash.Essentials.MobileControl.Messengers/MobileControlSimpleContent.cs

@@ -2,8 +2,15 @@
 
 namespace PepperDash.Essentials.AppServer
 {
+    /// <summary>
+    /// Generic container for simple mobile control message content with a single value
+    /// </summary>
+    /// <typeparam name="T">The type of the value contained in the message</typeparam>
     public class MobileControlSimpleContent<T>
     {
+        /// <summary>
+        /// Gets or sets the value of the message content
+        /// </summary>
         [JsonProperty("value", NullValueHandling = NullValueHandling.Ignore)]
         public T Value { get; set; }
     }