Update schema2html.py to add copyright info

Author: qiuosier

docs/source/yaml_schema/schema2html.py

@@ -1,3 +1,8 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*--
+
+# Copyright (c) 2021, 2022 Oracle and/or its affiliates.
+# Licensed under the Universal Permissive License v 1.0 as shown at https://oss.oracle.com/licenses/upl/
 """This script generates the HTML page containing tables to show the YAML schema.
 Usage:
 python schema2html path/to/yaml