add GPLv3

Makefile

@@ -1,3 +1,22 @@
+# range-gen creates a list of scene ranges based on a set of frames from the video.
+# Copyright (C) 2020 GenZmeY
+# mailto: genzmey@gmail.com
+#
+# This file is part of range-gen.
+#
+# range-gen 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, either version 3 of the License, or
+# (at your option) any later version.
+#
+# 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/>.
+
 NAME     = range-gen
 VERSION  = dev_$(shell date +%F_%T)
 GOCMD    = go