Makefile, manual, website: Bump copyright year

Happy 2018!

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 676400379abfdb7d1346c12ab592a88012b2fd5b)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

Makefile

@@ -2,7 +2,7 @@
 #
 # Copyright (C) 1999-2005 by Erik Andersen <andersen@codepoet.org>
 # Copyright (C) 2006-2014 by the Buildroot developers <buildroot@uclibc.org>
-# Copyright (C) 2014-2017 by the Buildroot developers <buildroot@buildroot.org>
+# Copyright (C) 2014-2018 by the Buildroot developers <buildroot@buildroot.org>
 #
 # 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

docs/manual/manual.txt

@@ -12,7 +12,7 @@ It is licensed under the GNU General Public License, version 2. Refer to the
 http://git.buildroot.org/buildroot/tree/COPYING[COPYING] file in the Buildroot
 sources for the full text of this license.
 
-Copyright (C) 2004-2017 The Buildroot developers
+Copyright (C) 2004-2018 The Buildroot developers
 
 image::logo.png[]
 

docs/website/copyright.txt

@@ -1,6 +1,6 @@
 
 The code and graphics on this website (and it's mirror sites, if any) are
-Copyright (c) 1999-2005 by Erik Andersen, 2006-2014 The Buildroot
+Copyright (c) 1999-2005 by Erik Andersen, 2006-2018 The Buildroot
 developers. All rights reserved.
 
 Documents on this Web site including their graphical elements, design, and