point to GH for the full list of contributors

AUTHORS

@@ -36,12 +36,7 @@ Even Rouault <even.rouault@spatialys.com>
 Kurt Schwehr <schwehr@gmail.com>
 
 Contributors
-................................................................................
-
-Brent Fraser <bfraser@geoanalytic.com>
-Chris Stuber <imap@chesapeake.net>
-Craig Bruce <cbruce@cubewerx.com>
-Victor Osipkov <vctos@email.com>
-Andrea Antonello <andrea.antonello@hydrologis.com>
-Knud Poder
+--------------------------------------------------------------------------------
 
+The full list of contributors can be found on GitHub
+https://github.com/OSGeo/proj.4/graphs/contributors