add missing sample (#290)

* add missing sample

* test

Author: mairaw

xml/System.Xml.Serialization/XmlIncludeAttribute.xml

@@ -60,7 +60,7 @@
 ## Examples  
  The following example shows three classes, two of which inherit from the third. The example applies the <xref:System.Xml.Serialization.XmlIncludeAttribute> to a method that returns an instance of one of the derived classes.  
   
-  
+[!code-aspx-csharp[sourcecs](~/samples/snippets/csharp/VS_Snippets_Remoting/Classic XmlIncludeAttribute Example/CS/sourcecs.asmx)]
   
  ]]></format>
     </remarks>
@@ -184,4 +184,4 @@
       </Docs>
     </Member>
   </Members>
-</Type>
+</Type>