Simplify the demo, make it more verbose

So people see how the API is used.
using vectors of structs with parameters is very compact but
is harder on the reader of a new API

examples/dockwidgets/MyMainWindow.h

@@ -27,5 +27,6 @@ public:
     explicit MyMainWindow(KDDockWidgets::MainWindowOptions options, QWidget *parent = nullptr);
 
 private:
+    KDDockWidgets::DockWidgetBase* newDockWidget();
     QMenu *m_toggleMenu = nullptr;
 };