update docs and license

src/dikdik/yamlv2.py

@@ -1,4 +1,20 @@
-
+#!/usr/bin/env python
+#
+# This file is part of dik-dik (https://github.com/mbovo/dikdik).
+# Copyright (c) 2020-2023 Manuel Bovo.
+#
+# 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 <http://www.gnu.org/licenses/>.
+#
 from ruamel.yaml import CommentedMap, CommentedSeq
 from typing import Callable, Any
 from re import Pattern