various changes:

- added copying in every file
- disasembled rootCmd into separate wrapper func
- print usage if no file and no stdin

mkrel.sh

@@ -1,5 +1,21 @@
 #!/bin/bash
 
+# Copyright © 2022 Thomas von Dein
+
+# 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, 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 <http://www.gnu.org/licenses/>.
+
+
 # get list with: go tool dist list
 DIST="darwin/amd64
 freebsd/amd64