diff --git a/docs/mdlstyle.rb b/docs/mdlstyle.rb
index f738818..ab3dc59 100644
--- a/docs/mdlstyle.rb
+++ b/docs/mdlstyle.rb
@@ -1,3 +1,21 @@
+# markdownlint(mdl) style rules
+# Rule descriptions:
+#  https://github.com/markdownlint/markdownlint/blob/master/docs/RULES.md
+
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed 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.
+
 # use all rules
 all