Declared GPLv3 license

firmware/Makefile

@@ -1,3 +1,20 @@
+#############################################################################
+#  MIDI Footswitch                                                          #
+#  Copyright (C) 2014-2018  Stefan Kalscheuer                               #
+#                                                                           #
+#  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     #
+#  the Free Software Foundation version 3.                                  #
+#                                                                           #
+#  This program is distributed in the hope that it will be useful,          #
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of           #
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            #
+#  GNU General Public License for more details.                             #
+#                                                                           #
+#   You should have received a copy of the GNU General Public License       #
+#   along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
+#############################################################################
+
 # Include environment config
 include Makefile.config