chore(githooks): add AGPL license header to commit-msg hook

.githooks/commit-msg

@@ -1,4 +1,21 @@
 #!/bin/sh
 
+#
+# Copyright 2016-present the IoT DC3 original author or authors.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+
 dc3/bin/commit_msg_lint.py "$1"