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.

tests/scripts/docker_env.sh

@@ -2,10 +2,6 @@
 
 # docker_env.sh
 #
-# This file is part of mbed TLS (https://tls.mbed.org)
-#
-# Copyright (c) 2018-2019, ARM Limited, All Rights Reserved
-#
 # Purpose
 # -------
 #
@@ -23,6 +19,23 @@
 # Running this script directly will check for Docker availability and set up
 # the Docker image.
 
+# 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)
+
 
 # default values, can be overridden by the environment
 : ${MBEDTLS_DOCKER_GUEST:=xenial}