Add link to CertValidation example

Author: mythz

src/ServiceStack.Redis/RedisConfig.cs

@@ -5,6 +5,8 @@ namespace ServiceStack.Redis
     public class RedisConfig
     {
         public static LocalCertificateSelectionCallback CertificateSelectionCallback { get; set; }
+
+        //Example at: http://msdn.microsoft.com/en-us/library/office/dd633677(v=exchg.80).aspx 
         public static RemoteCertificateValidationCallback CertificateValidationCallback { get; set; }
     }
 }