moving mailing list to discuss.graphhopper.com

README.md

@@ -32,7 +32,7 @@ Get Started
 
 Read through our Documentation ([0.5](https://github.com/graphhopper/graphhopper/blob/0.5/docs/index.md), [unstable](https://github.com/graphhopper/graphhopper/blob/master/docs/index.md)), 
 ask questions on [Stackoverflow](http://stackoverflow.com/questions/tagged/graphhopper)
-and sign up to the [mailing list](http://graphhopper.com/#developers).
+and sign up to the [discussion](https://discuss.graphhopper.com/).
 
 
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