Help Window: Add contents view to side bar

Change-Id: Id690c71471ed9a61bd7a926db70e1b1fb9fac8ab
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/help/helpwidget.h

@@ -140,6 +140,7 @@ private:
 
     Core::MiniSplitter *m_sideBarSplitter;
     Core::SideBar *m_sideBar;
+    QAction *m_contentsAction;
     QAction *m_indexAction;
     QAction *m_bookmarkAction;
 };