add gui programming topic link

Author: x4nth055

README.md

@@ -209,7 +209,7 @@ This is a repository of all the tutorials of [The Python Code](https://www.thepy
     - [Asynchronous Tasks with Celery in Python](https://www.thepythoncode.com/article/async-tasks-with-celery-redis-and-flask-in-python). ([code](https://github.com/bassemmarji/flask_sync_async))
     - [How to Build a CRUD App with Flask and SQLAlchemy in Python](https://www.thepythoncode.com/article/building-crud-app-with-flask-and-sqlalchemy). ([code](web-programming/bookshop-crud-app-flask))
 
-- ### GUI Programming
+- ### [GUI Programming](https://www.thepythoncode.com/topic/gui-programming)
     - [How to Make a Text Editor using Tkinter in Python](https://www.thepythoncode.com/article/text-editor-using-tkinter-python). ([code](gui-programming/text-editor))
     - [How to Make a Button using PyGame in Python](https://www.thepythoncode.com/article/make-a-button-using-pygame-in-python). ([code](gui-programming/button-in-pygame))
     - [How to Make a Drawing Program in Python](https://www.thepythoncode.com/article/make-a-drawing-program-with-python). ([code](gui-programming/drawing-tool-in-pygame))