message: add 2020 foundation copyright
diff: @@ -3,6 +3,7 @@ Copyright 2016 OpenMarket Ltd
  Copyright 2017 Vector Creations Ltd
  Copyright 2019 New Vector Ltd
  Copyright 2019 Michael Telatynski <7t3chguy@gmail.com>
  +Copyright 2020 The Matrix.org Foundation C.I.C.
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  