Adds missing README, CHANGELOG and LICENSE files

permission_handler_windows/AUTHORS

+
+# Below is a list of people and organizations that have contributed
+# to the Flutter project. Names should be added to the list like so:
+#
+#   Name/Organization <email address>
+
+Baseflow <hello@baseflow.com>
+Alexandre Zollinger Chohfi <alzollin@microsoft.com>
+Maurits van Beusekom <maurits@baseflow.com>

permission_handler_windows/CHANGELOG.md

+## 0.1.0
+
+* Adds an initial implementation of Windows support for the permission_handler plugin.

permission_handler_windows/LICENSE

+MIT License
+
+Copyright (c) 2018 Baseflow
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

permission_handler_windows/README.md

+# permission_handler_windows
+
+[![pub package](https://img.shields.io/pub/v/permission_handler_windows.svg)](https://pub.dartlang.org/packages/permission_handler_windows) ![Build status](https://github.com/Baseflow/flutter-permission-handler/workflows/permission_handler_android/badge.svg?branch=master) [![style: flutter lints](https://img.shields.io/badge/style-flutter_lints-40c4ff.svg)](https://pub.dev/packages/flutter_lints)
+
+The official Windows implementation of the [permission_handler](https://pub.dev/packages/permission_handler) plugin by [Baseflow](https://baseflow.com).
+
+## Usage
+
+Starting from version 9.2.0 of the [permission_handler](https://pub.dev/packages/permission_handler) plugin this is the endorsed Windows implementation. This means it will automatically be added to your dependencies when you depend on `permission_handler: ^9.2.0` in your applications pubspec.yaml.
+
+More detailed instructions on using the API can be found in the [README.md](../permission_handler/README.md) of the [permission_handler](https://pub.dev/packages/permission_handler) package.
+
+## Issues
+
+Please file any issues, bugs or feature requests as an issue on our [GitHub](https://github.com/Baseflow/flutter-permission-handler/issues) page. Commercial support is available, you can contact us at <hello@baseflow.com>.
+
+## Want to contribute
+
+If you would like to contribute to the plugin (e.g. by improving the documentation, solving a bug or adding a cool new feature), please carefully review our [contribution guide](../CONTRIBUTING.md) and send us your [pull request](https://github.com/Baseflow/flutter-permission-handler/pulls).
+
+## Author
+
+This permission_handler plugin for Flutter is developed by [Baseflow](https://baseflow.com).