Add in licensing notice

+###################################################################################
+
+The following modifications follow Apache License 2.0 from shiguredo.
+
+https://github.com/livekit/client-sdk-android/commit/f6983a0749e86fa8b5d8633ac7d20459e0cec5ee
+
+Apache License 2.0
+
+Copyright 2017, Lyo Kato <lyo.kato at gmail.com> (Original Author)
+Copyright 2017-2021, Shiguredo Inc.
+
+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.
+
+#####################################################################################