Add listener for HeartbeatEvent to refresh zuul routes

Fixes gh-1084

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

@@ -1121,7 +1121,7 @@ specified as an ant-style pattern, so "/myusers/{asterisk}" only matches one
 level, but "/myusers/{all}" matches hierarchically.
 
 The location of the backend can be specified as either a "serviceId"
-(for a Eureka service) or a "url" (for a physical location), e.g.
+(for a service from discovery) or a "url" (for a physical location), e.g.
 
 .application.yml
 [source,yaml]
@@ -1286,6 +1286,18 @@ classpath, and otherwise they are initialized to a set of well-known
 Security. The assumption in this case is that the downstream services
 might add these headers too, and we want the values from the proxy.
 
+=== The Routes Endpoint
+
+If you are using `@EnableZuulProxy` with tha Spring Boot Actuator you
+will enable (by default) an additional endpoint, available via HTTP as
+`/routes`. A GET to this endpoint will return a list of the mapped
+routes. A POST will force a refresh of the existing routes (e.g. in
+case there have been changes in the service catalog).
+
+NOTE: the routes should respond automatically to changes in the
+service catalog, but the POST to /routes is a way to force the change
+to happen immediately.
+
 === Strangulation Patterns and Local Forwards
 
 A common pattern when migrating an existing application or API is to