add link at bottom

Author: greg-lindsay

articles/traffic-manager/traffic-manager-how-it-works.md

@@ -75,6 +75,8 @@ The recursive DNS service caches the DNS responses it receives. The DNS resolver
 
 * [Why am I seeing an HTTP error when using Traffic Manager?](./traffic-manager-faqs.md#why-am-i-seeing-an-http-error-when-using-traffic-manager)
 
+* [How can I resolve a 500 (Internal Server Error) when using Traffic Manager?](./traffic-manager-faqs.md#how-can-i-resolve-a-500-internal-server-error-when-using-traffic-manager)
+
 * [What is the performance impact of using Traffic Manager?](./traffic-manager-faqs.md#what-is-the-performance-impact-of-using-traffic-manager)
 
 * [What application protocols can I use with Traffic Manager?](./traffic-manager-faqs.md#what-application-protocols-can-i-use-with-traffic-manager)