Added link about external kestrel access

Author: ebicoglu

doc/Development-Guide-Xamarin.html

@@ -130,10 +130,10 @@ <h4>Host</h4>
 <img class="img-thumbnail" alt="MVC Started" src="images/xamarin-mvc-started.png" />
 </p>
 <div class="bs-callout bs-callout-warning">
-	<strong><i class="fa fa-warning"></i>Warning</strong>
+	<strong><i class="fa fa-warning"></i> Warning</strong>
 	<div>
 		Do not start Web.Mvc or Web.Host project via Visual Studio. Default settings 
-		of Visual Studio does not allow connections except localhost.</div>
+		of Visual Studio does not allow external connections. For more info you can read <a href="https://weblog.west-wind.com/posts/2016/Sep/28/External-Network-Access-to-Kestrel-and-IIS-Express-in-ASPNET-Core">External Network Access to Kestrel and IIS Express in ASP.NET Core</a></div>
 </div>
 <p><font color="#339933"><i class="fa fa-info-circle"></i> We have successfully started 
 host. Now we can configure Xamarin app to connect this host.</font></p>