Added slashdoc.

src/Renci.SshNet/Messages/Connection/ChannelOpenConfirmationMessage.cs

@@ -27,6 +27,12 @@
         /// </value>
         public uint MaximumPacketSize { get; private set; }
 
+        /// <summary>
+        /// Gets the size of the message in bytes.
+        /// </summary>
+        /// <value>
+        /// The size of the messages in bytes.
+        /// </value>
         protected override int BufferCapacity
         {
             get