Help Window: Add search view to side bar

Change-Id: If3acbad9694b6d1a3441007a9fa9c13a3738aa5f
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>

src/plugins/help/helpwidget.h

@@ -144,6 +144,7 @@ private:
     QAction *m_contentsAction;
     QAction *m_indexAction;
     QAction *m_bookmarkAction;
+    QAction *m_searchAction;
 };
 
 } // Internal