Added C++ GUI applications (beginner to advanced) (#9833)

Added C++ GUI applications (beginner to advanced) from CodeBeauty YouTube channel.

courses/free-courses-en.md

@@ -335,6 +335,7 @@
 * [C++](https://www.youtube.com/playlist?list=PLlrATfBNZ98dudnM48yfGUldqGD0S4FFb) - The Cherno
 * [C++ Compilation, Linking, and Makefiles](https://youtube.com/playlist?list=PLNUvpxaaFJ_i6BYqbxTVeK5AOcFzQbboQ) - Amy Larson
 * [C++ For Programmers](https://www.udacity.com/course/c-for-programmers--ud210) - Catherine Gamboa (Udacity)
+* [C++ GUI applications (beginner to advanced)](https://www.youtube.com/playlist?list=PL43pGnjiVwgQakzRxpt2amqN9f7-tRtc_) - Saldina Nurak (CodeBeauty)
 * [C++ Object-Oriented Programming](https://www.youtube.com/playlist?list=PL43pGnjiVwgTJg7uz8KUGdXRdGKE0W_jN) - Saldina Nurak (CodeBeauty)
 * [C++ Programming](https://www.youtube.com/playlist?list=PLBlnK6fEyqRh6isJ01MBnbNpV3ZsktSyS) - Neso Academy
 * [C++ Programming](https://www.youtube.com/playlist?list=PLfu_Bpi_zcDOtpXhhxL-P1wu0VkwNRXwC) - Kody Simpson