add summary comment.

src/DotNetCore.CAP/ICallbackPublisher.cs

@@ -3,8 +3,14 @@ using DotNetCore.CAP.Models;
 
 namespace DotNetCore.CAP
 {
+    /// <summary>
+    /// A callback that is sent to Productor after a successful consumer execution
+    /// </summary>
     public interface ICallbackPublisher
     {
+        /// <summary>
+        /// Publish a callback message
+        /// </summary>
         Task PublishAsync(CapPublishedMessage obj);
     }
 }

src/DotNetCore.CAP/IConsumerClient.cs

@@ -6,7 +6,7 @@ namespace DotNetCore.CAP
 {
     /// <inheritdoc />
     /// <summary>
-    /// consumer client
+    /// Message queue consumer client
     /// </summary>
     public interface IConsumerClient : IDisposable
     {