Update license with additional terms

Fixes Yoast/wordpress-seo#9229

LICENSE.md → license.txt

@@ -618,57 +618,25 @@ an absolute waiver of all civil liability in connection with the
 Program, unless a warranty or assumption of liability accompanies a
 copy of the Program in return for a fee.
 
-                     END OF TERMS AND CONDITIONS
+  18. Additional terms
 
-            How to Apply These Terms to Your New Programs
+  In the light of Article 7 of the GPL license, the following additional 
+terms apply:
 
-  If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these terms.
+  a) You are prohibited to make misrepresentations of the origin of that 
+material, or to require that modified versions of such material be marked 
+in reasonable ways as different from the original version;
 
-  To do so, attach the following notices to the program.  It is safest
-to attach them to the start of each source file to most effectively
-state the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
+  b) You are limited in the use for publicity purposes of names of 
+licensors or authors of the material;
 
-    {one line to give the program's name and a brief idea of what it does.}
-    Copyright (C) {year}  {name of author}
+  c) You are declined any grant of rights under trademark law for use of 
+the trade names, trademarks, or service marks of YOAST B.V.;
 
-    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 the License, or
-    (at your option) any later version.
+  d) You are required to indemnify licensors and authors of that material 
+by anyone who conveys the material (or modified versions of it) with 
+contractual assumptions of liability to the recipient, for any liability 
+that these contractual assumptions directly impose on those licensors and 
+authors.
 
-    This program is distributed in the hope that it will be useful,
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-    GNU General Public License for more details.
-
-    You should have received a copy of the GNU General Public License
-    along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-Also add information on how to contact you by electronic and paper mail.
-
-  If the program does terminal interaction, make it output a short
-notice like this when it starts in an interactive mode:
-
-    {project}  Copyright (C) {year}  {fullname}
-    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
-    This is free software, and you are welcome to redistribute it
-    under certain conditions; type `show c' for details.
-
-The hypothetical commands `show w' and `show c' should show the appropriate
-parts of the General Public License.  Of course, your program's commands
-might be different; for a GUI interface, you would use an "about box".
-
-  You should also get your employer (if you work as a programmer) or school,
-if any, to sign a "copyright disclaimer" for the program, if necessary.
-For more information on this, and how to apply and follow the GNU GPL, see
-<http://www.gnu.org/licenses/>.
-
-  The GNU General Public License does not permit incorporating your program
-into proprietary programs.  If your program is a subroutine library, you
-may consider it more useful to permit linking proprietary applications with
-the library.  If this is what you want to do, use the GNU Lesser General
-Public License instead of this License.  But first, please read
-<http://www.gnu.org/philosophy/why-not-lgpl.html>.
+END OF TERMS AND CONDITIONS