Update free-courses-en.md (#3343)

free-courses-en.md

@@ -426,6 +426,7 @@
 
 ### TypeScript
 
+* [Introduction to TypeScript](https://www.udemy.com/typescript/) - Daniel Stern (Udemy)
 * [TypeScript Fast Crash Course](https://www.udemy.com/typescript-fast-crash-course/) - Edwin Diaz, Coding Faculty Solutions (Udemy)