Bootstrap course (#9915)

* Add Java and Kotlin free courses in pt-BR

* add bootstrap course

courses/free-courses-en.md

@@ -776,6 +776,7 @@
 * [Bootstrap tutorial for beginners](https://www.youtube.com/playlist?list=PL6n9fhu94yhXd4xnk-j5FGhHjUv1LsF0V) - kudvenkat
 * [Complete Bootstrap 4 course - build 3 projects](https://www.udemy.com/course/bootstrap-4-tutorials) - Igneus Technologies (Udemy)
 * [Complete Bootstrap Crash Course \| Bootstrap 4 Tutorial](https://www.youtube.com/watch?v=ZfRn9VJzdGA) - Julio Codes
+* [Gentle Introduction to Bootstrap 5 for Beginners](https://www.youtube.com/playlist?list=PLErOmyzRKOCr47pRGOswKcgzGyetNRdHZ) - Deborah Kurata
 * [Introduction to Bootstrap - A Tutorial](https://www.classcentral.com/course/edx-introduction-to-bootstrap-a-tutorial-3338) - Microsoft via edX (Class Central)
 * [Learn Bootstrap 4 for free](https://scrimba.com/learn/bootstrap4) - Neil Rowe (Scrimba)
 * [Learn Bootstrap 4 in this free 10-part course](https://www.freecodecamp.org/news/want-to-learn-bootstrap-4-heres-our-free-10-part-course-happy-easter-35c004dc45a4/) - Per Harald Borgen (Freecodecamp)