Update documentation (#312)

* fix GPL version

* Fix Copyright Symbol

* Refer to CADET-Verification in testing guide

---------

Co-authored-by: Lanzrath, Hannah <[email protected]>
Co-authored-by: Jan Breuer <[email protected]>

LICENSE.txt

@@ -1,6 +1,6 @@
 COPYRIGHT AND LICENSE NOTICE
 
-Copyright � 2008-2024: The CADET Authors, please see the CONTRIBUTING.md file.
+Copyright (C) 2008-2024: The CADET Authors, please see the CONTRIBUTING.md file.
 
 This program is free software: you can redistribute it and/or modify it under the terms of the
 GNU General Public License as published by the Free Software Foundation, either version 3 of

README.rst

@@ -81,7 +81,7 @@ Donations
 License
 -------
 
-Released under GPL v3. License (see `LICENSE.txt <https://github.com/cadet/cadet-core/blob/master/LICENSE.txt>`_)::
+Released under GPL v3.0 License (see `LICENSE.txt <https://github.com/cadet/cadet-core/blob/master/LICENSE.txt>`_)::
 
 Acknowledgments
 ---------------

doc/developer_guide/release_new_version.rst

@@ -13,7 +13,7 @@ Release checklist
   - The release tests contain extensive testing that is not included in our CI, such as EOC tests.
     Running these tests might take a while and this should be done on the server.
   - Some tests are implemented in CADET-Core, and can be run with the [ReleaseCI] flag.
-  - More tests are implemented in Python, the code can be found on the `Core_tests branch of CADET-Reference <https://jugit.fz-juelich.de/IBG-1/ModSim/cadet/cadet-reference/-/tree/CADET-Core_tests>`_
+  - More tests are implemented in Python, the code can be found in `CADET-Verification <https://github.com/cadet/CADET-Verification>`_
   Compare the results with the previous run.
   The release process can only be continued if the results are reasonable.