Doc: remove link to Nokia UX desing Library

This site is now mostly about designing for devices that
do not support Qt.

Change-Id: I8b092f85ada7de770ed8e61307cb6f48c5a2701e
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

doc/src/overview/mobile-app-design.qdoc

@@ -115,8 +115,4 @@
 
     \endlist
 
-    For more information about user experience techniques for mobile devices,
-    see the \l{http://www.developer.nokia.com/Resources/Library/Design_and_UX}
-    on Nokia Developer.
-
  */