Readme: Add tilestache repo

Author: tordans

README.md

@@ -7,6 +7,7 @@ An overview of the map data avaliable on the server.
 * [luftbilder.berlin.codefor.de](https://luftbilder.berlin.codefor.de) is focussed on areal images from differnt years [Github](https://github.com/codeforberlin/luftbilder.berlin.codefor.de) 
 * ~~https://tiles.codefor.de/ shows the same data as this site [Github](https://github.com/jochenklar/tiles)~~ (Archived)
 * [github.com/codeforberlin/mapproxy-config](https://github.com/codeforberlin/mapproxy-config) is a map proxy for some imagery layers by the City of Berlin
+* [github.com/codeforberlin/tilestache-config](https://github.com/codeforberlin/tilestache-config) is the config for serving areal imagery from file ([config](https://github.com/codeforberlin/tilestache-config/blob/master/config.json))
 
 
 ## Data source