Replace -Dokumentationsprojekt with Documentation Project

Author: rbuj

help/C/index.docbook

@@ -25,7 +25,7 @@ text-based commands through a shell such as Bash.
      </abstract>
      <copyright> 
         <year>2015</year> 
-        <holder>MATE-Dokumentationsprojekt</holder> 
+        <holder>MATE Documentation Project</holder>
      </copyright>
      <copyright>
         <year>2009</year>