[4.0] Remove outdated link (#25598) (port of #25597)

Author: brianteeman

README.md

@@ -69,6 +69,5 @@ Do you want to improve Joomla?
 Copyright
 ---------------------
 * Copyright (C) 2005 - 2019 Open Source Matters. All rights reserved.
-* [Special Thanks](https://docs.joomla.org/Special:MyLanguage/Joomla!_Credits_and_Thanks)
 * Distributed under the GNU General Public License version 2 or later
 * See [License details](https://docs.joomla.org/Special:MyLanguage/Joomla_Licenses)

README.txt

@@ -68,6 +68,5 @@
 
 Copyright:
 	* Copyright (C) 2005 - 2019 Open Source Matters. All rights reserved.
-	* Special Thanks: https://docs.joomla.org/Special:MyLanguage/Joomla!_Credits_and_Thanks
 	* Distributed under the GNU General Public License version 2 or later
-	* See Licenses details at https://docs.joomla.org/Special:MyLanguage/Joomla_Licenses
+	* See License details at https://docs.joomla.org/Special:MyLanguage/Joomla_Licenses