Add Contributors file

CONTRIBUTORS

+2019-2020 Copyright Sosthène Guédon
+2020 Copyright Louis Cousturian
+2019 Copyright Olivér Facklam
+2019 Copyright Hadrien Renaud
+2019 Copyright Mael Madon
+2016-2019 Copyright Clément Durand
+2018 Copyright Wilson Jallet 
+2018 Copyright Guangshuo Chen
+2015-2016 Copyright Denis Merigoux

source/polytechnique.dtx

@@ -2,7 +2,6 @@
 %
 % For explanation on this file, see http://texdoc.net/texmf-dist/doc/latex/dtxtut/dtxtut.pdf
 %
-% Copyright (C) 2015 i by Denis Merigoux
 %
 % This file may be distributed and/or modified under the
 % conditions of the LaTeX Project Public License, either
@@ -30,7 +29,6 @@
 \preamble
 This is a generated file.
 
-Copyright (C) 2015 by Denis Merigoux
 
 This file may be distributed and/or modified under the
 conditions of the LaTeX Project Public License, either

source/polytechnique.sty

@@ -7,7 +7,6 @@
 %% polytechnique.dtx  (with options: `package')
 %% This is a generated file.
 %% 
-%% Copyright (C) 2015 by Denis Merigoux
 %% 
 %% This file may be distributed and/or modified under the
 %% conditions of the LaTeX Project Public License, either