Added client documentation.

Source/MQTTnet/Client/Disconnecting/IMqttClientDisconnectedHandler.cs

@@ -4,6 +4,11 @@ namespace MQTTnet.Client.Disconnecting
 {
     public interface IMqttClientDisconnectedHandler
     {
+        /// <summary>
+        /// Handles the events when a client gets disconnected.
+        /// </summary>
+        /// <param name="eventArgs">The event args.</param>
+        /// <returns>A <see cref="Task"/> representing any asynchronous operation.</returns>
         Task HandleDisconnectedAsync(MqttClientDisconnectedEventArgs eventArgs);
     }
 }

Source/MQTTnet/Client/Disconnecting/MqttClientDisconnectOptions.cs

@@ -2,8 +2,16 @@
 {
     public class MqttClientDisconnectOptions
     {
+        /// <summary>
+        /// Gets or sets the reason code.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
         public MqttClientDisconnectReason ReasonCode { get; set; } = MqttClientDisconnectReason.NormalDisconnection;
 
+        /// <summary>
+        /// Gets or sets the reason string.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
         public string ReasonString { get; set; }
     }
 }

Source/MQTTnet/Client/Disconnecting/MqttClientDisconnectedEventArgs.cs

@@ -15,12 +15,26 @@ namespace MQTTnet.Client.Disconnecting
             ReasonCode = reason;
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the client was connected or not.
+        /// </summary>
         public bool ClientWasConnected { get; }
 
+        /// <summary>
+        /// Gets the exception.
+        /// </summary>
         public Exception Exception { get; }
 
+        /// <summary>
+        /// Gets the authentication result.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
         public MqttClientAuthenticateResult AuthenticateResult { get; }
 
+        /// <summary>
+        /// Gets or sets the reason.
+        /// Hint: MQTT 5 feature only.
+        /// </summary>
         public MqttClientDisconnectReason Reason { get; set; }
 
         [Obsolete("Please use 'Reason' instead. This property will be removed in the future!")]