Add more federation.

README.md

@@ -25,7 +25,8 @@ People can use the Go binary made based on this repo. But we'll also have it as
 Currently we have one Prometheus server per GitLab installation.
 We should continue to use this server for GitLab metrics, federated metrics from other servers, and alerting.
-But every application should get its own Prometheus pod to monitor that application in the future.
+But every application deployed with GitLab should get its own Prometheus pod to monitor that application in the future.
+The main Prometheus server can get metrics from the application specific servers to help with alerting.
 ## Structure