Added copyright comment to the header of a file

Signed-off-by: Kuuuna98 <yunaghgh@naver.com>

src/main/java/com/owncloud/android/ui/activity/PassCodeActivity.java

@@ -6,6 +6,7 @@
  *   @author David A. Velasco
  *   Copyright (C) 2011 Bartek Przybylski
  *   Copyright (C) 2015 ownCloud Inc.
+ *   Copyright (C) 2020 Kwon Yuna <yunaghgh@naver.com>
  *
  *   This program is free software: you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License version 2,