Update readme.md

Author: warapetch

desktop clock/readme.md

@@ -6,3 +6,10 @@
 ![image](https://user-images.githubusercontent.com/6521378/153115547-c6487d03-8a0b-406e-aacf-0166ac7cd19d.png)
 
 ![image](https://user-images.githubusercontent.com/6521378/153115591-eb738d04-91d9-4402-baaf-6fc4fc57105b.png)
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+วีดีโอ สอนการพัฒนาโปรแกรม \n
+![วิดีโอ](https://img.youtube.com/vi/ziBgqkH6tmE/0.jpg)
+
+<!-- Corresponsing iframe markup copied from youtube embed of the corresponding video -->
+<iframe width="560" height="315" src="https://www.youtube.com/embed/ziBgqkH6tmE" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>