DOC: added hint for testing running server

README_SETUP.md

@@ -110,6 +110,13 @@ Done!
 
 `$ make run`
 
+This can take a while. Once you see `Starting caosdb.server.CaosDBServer
+application` the server is ready and you can try it out by connecting with a
+client, e.g. the web client, if you installed it. Typically, you just need to
+type `https://localhost:10443` in your Browser, assuming you used 10443 as port.
+Note, that you will get a security warning if you are using a self-signed
+certificate.
+
 # Run Unit Tests
 
 `$ make test`