README: add note on gateway, github URL

Author: mhaas

README.md

@@ -1,12 +1,29 @@
+# WifiDog #
+
 The WiFi Guard Dog project is a complete and embeddable captive portal
 solution for wireless community groups or individuals who wish to open a
-free HotSpot while still preventing abuse of their Internet connection.
+free hotspot while still preventing abuse of their Internet connection.
 
 The project's homepage is:
 	http://dev.wifidog.org/
 
-Mailing list interface:
-	http://listes.ilesansfil.org/cgi-bin/mailman/listinfo/wifidog
+Development happens on GitHub:
+	https://github.com/wifidog/
+
+## WifiDog Gateway ##
+
+WifiDog consists of two parts:
+
+* auth server
+* client daemon (the gateway)
+
+This repository contains the client daemon. The client typically runs on
+embedded hardware, e.g. the hotspot itself. The client is responsible for
+redirecting the user to the auth server where they may authenticate
+themselves. Depending on the response of the auth server, the client
+lifts the access restrictions for the user.
 
-The project's software is released under the GPL license and is copyright it's respective owners.
+## License ##
+The project's software is released under the GPL license and is copyrighted
+by its respective owners. See COPYING for details.