Document QAction::MenuRole not working on submenus.
Document QAction::MenuRole not working on submenus.

We could do it or we couldn't. It's simply a judgement call and I think
the comments in the task are a good argument for NOT doing it.

Task-number: 227875

pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,RLovelett/qt,radekp/qt,KDE/qt,RLovelett/qt,radekp/qt,igor-sfdc/qt-wk,KDE/qt,pruiz/wkhtmltopdf-qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,RLovelett/qt,RLovelett/qt,radekp/qt,KDE/qt,radekp/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,KDE/qt,radekp/qt,KDE/qt,igor-sfdc/qt-wk,radekp/qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,RLovelett/qt,radekp/qt,RLovelett/qt,KDE/qt,igor-sfdc/qt-wk,KDE/qt,RLovelett/qt,KDE/qt,pruiz/wkhtmltopdf-qt,RLovelett/qt,igor-sfdc/qt-wk,igor-sfdc/qt-wk,igor-sfdc/qt-wk,pruiz/wkhtmltopdf-qt,RLovelett/qt,igor-sfdc/qt-wk,radekp/qt,pruiz/wkhtmltopdf-qt,radekp/qt,RLovelett/qt,radekp/qt