Merge torrust#98: feat: update licence files

247a043 feat: update licence files (Cameron Garnham)

Pull request description:

  In this comment we update the licence files to make the format more simple.

ACKs for top commit:
  da2ce7:
    ACK 247a043

Tree-SHA512: 55e5e76fd94f197854a8d9f9d55b0c6ae4303026642a652b95a446273d7e3a6564224fff115678a54291eb78c2feb6f7a550b6ab745e421011398f62333370fa

COPYRIGHT

@@ -0,0 +1,12 @@
+Copyright 2023 in the Torrust-Index-Backend project are retained by their contributors. No
+copyright assignment is required to contribute to the Torrust-Index-Backend project.
+
+Some files include explicit copyright notices and/or license notices.
+
+Except as otherwise noted (below and/or in individual files), Torrust-Index-Backend is
+licensed under the GNU Affero General Public License, Version 3.0 <LICENSE-AGPL_3_0>. This license applies to all files in the Torrust-Index-Backend project, except as noted below.
+
+Except as otherwise noted (below and/or in individual files), Torrust-Index-Backend is licensed under the MIT-0 license <LICENSE-MIT_0> for all commits made after 5 years of merging. This license applies to the version of the files merged into the Torrust-Index-Backend project at the time of merging, and does not apply to subsequent updates or revisions to those files.
+
+The contributors to the Torrust-Index-Backend project disclaim all liability for any damages or losses that may arise from the use of the project.
+