Doc: Remove Qt Designer manual from the licensing group

The Qt licensing information page will link to the Qt Designer
-specific information directly.

Task-number: QTBUG-35362
Change-Id: I293402a8024f33b68446497a50b9782803d20761
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>

src/designer/src/designer/doc/src/designer-manual.qdoc

@@ -2802,7 +2802,6 @@ pixmap property in the property editor.
     \title Qt Designer License Information
     \contentspage {Qt Designer Manual}{Contents}
 
-    \ingroup licensing
     \brief License information for contributions to specific parts of the Qt
     Designer source code.