Add information on SimpleDiscoveryClient. Fixes gh-295.

Author: OlgaMaciaszek

docs/src/main/asciidoc/spring-cloud-openfeign.adoc

@@ -63,8 +63,7 @@ The load-balancer client above will want to discover the physical addresses
 for the "stores" service. If your application is a Eureka client then
 it will resolve the service in the Eureka service registry. If you
 don't want to use Eureka, you can simply configure a list of servers
-in your external configuration (see
-<<spring-cloud-ribbon-without-eureka,above for example>>).
+in your external configuration using https://cloud.spring.io/spring-cloud-static/spring-cloud-commons/current/reference/html/#simplediscoveryclient[`SimpleDiscoveryClient`].
 
 WARNING: In order to maintain backward compatibility, is used as the default load-balancer implementation.
 However, Spring Cloud Netflix Ribbon is now in maintenance mode, so we recommend using Spring Cloud LoadBalancer instead.