readme explaining gracedemo usage

readme.md

@@ -11,9 +11,48 @@ Additionally it is implemented using the same API as systemd providing [socket
 activation](http://0pointer.de/blog/projects/socket-activation.html)
 compatibility to also provide lazy activation of the server.
 
+
+Usage
+-----
+
 Demo HTTP Server with graceful termination and restart:
 https://github.com/daaku/go.grace/blob/master/gracedemo/demo.go
 
+1. Install the demo application
+
+        go get github.com/daaku/go.grace/gracedemo
+
+1. Start it in the first terminal
+
+        gracedemo
+
+   This will output something like:
+
+        2013/03/25 19:07:33 Serving [::]:48567, [::]:48568, [::]:48569 with pid 14642.
+
+1. In a second terminal start a slow HTTP request
+
+        curl 'http://localhost:48567/sleep/?duration=20s'
+
+1. In a third terminal trigger a graceful server restart (using the pid from your output):
+
+        kill -USR2 14642
+
+1. Trigger another shorter request that finishes before the earlier request:
+
+        curl 'http://localhost:48567/sleep/?duration=0s'
+
+
+If done quickly enough, this shows the second quick request will be served by
+the new process (as indicated by the PID) while the slow first request will be
+served by the first server. It shows how the active connection was gracefully
+served before the server was shutdown. It is also showing that at one point
+both the new as well as the old server was running at the same time.
+
+
+Documentation
+-------------
+
 http level graceful termination and restart:
 http://godoc.org/github.com/daaku/go.grace/gracehttp