Added link to Hello World Integration tests.

Author: mythz

src/ServiceStack.Hello/default.htm

@@ -672,11 +672,15 @@ <h4><b>[RestService("/hello")]</b></h4>
         without messy configuration and generated code mandated by other options.
     </p>
 
-    <a name="calling"></a>
+    <a name="clients"></a>
     <h2>Calling Web Services from Code</h2>
     <p>
         Using DTOs to define your web service interface makes it possible to provide strong-typed generic service clients without any code-gen or extra build-steps,
-        leading to a productive end-to-end type-safe communication gateway from client to server.
+        leading to a productive end-to-end type-safe communication gateway from client to server. 
+    </p>
+    <p>
+        All REST and ServiceClients share the same interfaces so they can easily be replaced (for increased perf/debuggability/etc) with a single line of code as seen in the  
+        <a href="https://github.com/ServiceStack/ServiceStack/blob/master/tests/ServiceStack.WebHost.IntegrationTests/Tests/HelloWorldServiceClientTests.cs">Hello Service Integration tests</a>.
     </p>
     <p>
         C#/.NET Clients can call the above Hello Service using any of the