add link to exitcode (#2535)

* add link to exitcode

* Update xml/System.Windows/Application.xml with suggestion

Co-Authored-By: Ron Petrusha <[email protected]>

Author: dsychin

xml/System.Windows/Application.xml

@@ -1990,6 +1990,7 @@ This example illustrates how to use XAML together with application-scope resourc
   
  This method can be called only from the thread that created the <xref:System.Windows.Application> object.  
   
+ See <xref:System.Environment.ExitCode%2A?displayProperty=nameWithType> for information on exit codes.
  ]]></format>
         </remarks>
         <permission cref="T:System.Security.Permissions.UIPermission">for permission to use all windows and user input events without restriction. Associated enumeration: <see cref="F:System.Security.Permissions.UIPermissionWindow.AllWindows" /></permission>
@@ -2296,4 +2297,4 @@ This example illustrates how to use XAML together with application-scope resourc
       </Docs>
     </Member>
   </Members>
-</Type>
+</Type>