Change license from ONF-Member-Only to Apache-2.0

Change-Id: If5c78f555fb737a18a3ae4c216ea3e2630b101bc
diff --git a/conf.py b/conf.py
index 3866491..af16176 100644
--- a/conf.py
+++ b/conf.py
@@ -1,3 +1,6 @@
+# SPDX-FileCopyrightText: 2021 Open Networking Foundation <info@opennetworking.org>
+# SPDX-License-Identifier: Apache-2.0
+
 # -*- coding: utf-8 -*-
 #
 # Configuration file for the Sphinx documentation builder.