add license header

Signed-off-by: Julien Le Dem <julien@apache.org>

Author: julienledem

proposals/1_BASE64_ENCODING.md

@@ -1,3 +1,21 @@
+<!--
+  - Licensed to the Apache Software Foundation (ASF) under one
+  - or more contributor license agreements.  See the NOTICE file
+  - distributed with this work for additional information
+  - regarding copyright ownership.  The ASF licenses this file
+  - to you under the Apache License, Version 2.0 (the
+  - "License"); you may not use this file except in compliance
+  - with the License.  You may obtain a copy of the License at
+  -
+  -   http://www.apache.org/licenses/LICENSE-2.0
+  -
+  - Unless required by applicable law or agreed to in writing,
+  - software distributed under the License is distributed on an
+  - "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  - KIND, either express or implied.  See the License for the
+  - specific language governing permissions and limitations
+  - under the License.
+  -->
 ---
 Author: Julien Le Dem
 Created: 2025-Aug-7

proposals/README.md

@@ -1,3 +1,21 @@
+<!--
+  - Licensed to the Apache Software Foundation (ASF) under one
+  - or more contributor license agreements.  See the NOTICE file
+  - distributed with this work for additional information
+  - regarding copyright ownership.  The ASF licenses this file
+  - to you under the Apache License, Version 2.0 (the
+  - "License"); you may not use this file except in compliance
+  - with the License.  You may obtain a copy of the License at
+  -
+  -   http://www.apache.org/licenses/LICENSE-2.0
+  -
+  - Unless required by applicable law or agreed to in writing,
+  - software distributed under the License is distributed on an
+  - "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  - KIND, either express or implied.  See the License for the
+  - specific language governing permissions and limitations
+  - under the License.
+  -->
 # Proposals
 
 This proposal process is intended for significantly impactful additions to the Parquet spec. The goal is to facilitate those projects and help them being contributed to Parquet.

proposals/_PROPOSAL_TEMPLATE.md

@@ -1,3 +1,21 @@
+<!--
+  - Licensed to the Apache Software Foundation (ASF) under one
+  - or more contributor license agreements.  See the NOTICE file
+  - distributed with this work for additional information
+  - regarding copyright ownership.  The ASF licenses this file
+  - to you under the Apache License, Version 2.0 (the
+  - "License"); you may not use this file except in compliance
+  - with the License.  You may obtain a copy of the License at
+  -
+  -   http://www.apache.org/licenses/LICENSE-2.0
+  -
+  - Unless required by applicable law or agreed to in writing,
+  - software distributed under the License is distributed on an
+  - "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+  - KIND, either express or implied.  See the License for the
+  - specific language governing permissions and limitations
+  - under the License.
+  -->
 # Proposal
 
 ---