[-release] Updating copyright notices.

Author: Sympa authors

configure.ac

@@ -7,6 +7,9 @@
 # Copyright (c) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
 # 2006, 2007, 2008, 2009, 2010, 2011 Comite Reseau des Universites
 # Copyright (c) 2011, 2012, 2013, 2014, 2015, 2016, 2017 GIP RENATER
+# Copyright 2017 The Sympa Community. See the AUTHORS.md file at the top-level
+# directory of this distribution and at
+# <https://github.com/sympa-community/sympa.git>.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by