Clean up file prologue comments
Update new files to include the same legalese as in aes.h. Editorial
touchups in Dockerfile and ssl-opt-in-docker.sh.
diff --git a/tests/docker/xenial/Dockerfile b/tests/docker/xenial/Dockerfile
index 4573af9..f16ae75 100644
--- a/tests/docker/xenial/Dockerfile
+++ b/tests/docker/xenial/Dockerfile
@@ -1,13 +1,27 @@
-#
-# This file is part of mbed TLS (https://tls.mbed.org)
-#
-# Copyright (c) 2018-2019, ARM Limited, All Rights Reserved
+# Dockerfile
#
# Purpose
-#
+# -------
# Defines a Docker container suitable to build and run all tests (all.sh),
# except for those that use a proprietary toolchain.
+# Copyright (C) 2006-2019, Arm Limited (or its affiliates), All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# 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.
+#
+# This file is part of Mbed TLS (https://tls.mbed.org)
+
FROM ubuntu:xenial
ARG MAKEFLAGS_PARALLEL=""