Added a new kotlin course (#10470)

* Added a new kotlin course

* Added a new Kotlin course

* Fixed Linter error and added a new kotlin course

* changed the course name

courses/free-courses-en.md

@@ -1128,6 +1128,7 @@
 * [Kotlin Tutorial](https://www.youtube.com/playlist?list=PLsyeobzWxl7rooJFZhc3qPLwVROovGCfh) - Telusko
 * [Kotlin Tutorial for Beginners: Basics and Fundamentals for Android](https://www.youtube.com/playlist?list=PLlxmoA0rQ-LwgK1JsnMsakYNACYGa1cjR) - Smartherd
 * [One hour Kotlin guide for beginners](https://www.udemy.com/course/one-hour-kotlin-guide-for-beginners) - Tutlets Kkang (Udemy)
+* [Teach Computer Science with Kotlin](https://kotlinlang.org/education/) - Kotlin
 * [Track: Kotlin Basics](https://hyperskill.org/tracks/18) - Hyperskill, JetBrains (Hyperskill)