link to the prototype in the README

Author: tuukka

README.md

@@ -4,4 +4,6 @@ HSL Navigator
 
 HSL Navigator is an open-source project initiated by Helsinki Region Transport HSL to eventually surpass its current journey planner service. The project aims to produce a new type of routing service with turn-by-turn navigation to cyclists and public transport passengers. The project also tests how to create a public service based on open-source development, various sources of open data as well as user-generated content.
 
-Read more in wiki https://github.com/HSLdevcom/hsl-navigator/wiki
+Read more in the wiki: https://github.com/HSLdevcom/hsl-navigator/wiki
+
+We have developed a test prototype called City Navigator with the [HSL Developer Community](http://dev.hsl.fi/) and [Code for Europe](http://codeforeurope.net/): https://github.com/codeforeurope/navigator-proto