Updated Qt DesignStudio showcase image and video link

Author: githubuser0xFFFF

README.md

@@ -354,7 +354,7 @@ Taken from the [Qt Blog](https://www.qt.io/blog/qt-design-studio-1.5-beta-releas
 
 > The most obvious change in [Qt Design Studio 1.5](https://www.qt.io/blog/qt-design-studio-1.5-beta-released) is the integration of dock widgets using the Qt Advanced Docking System. This allows the user to fully customize the workspace and also to undock any view into its own top level window. This especially improves the usability when using multiple screens.
 
-![Qt Design Studio](doc/showcase_qt_design_studio.png)
+[![Qt Design Studio](doc/showcase_qt_design_studio_video.png)](https://youtu.be/za9KBWcFXEw?t=84)
 
 ### [QmixElements](https://www.cetoni.com/products/qmixelements/)