add FE web development with react course from fireship.io (#6440)

* add FE web development with react course

* minor change on title and instructor

courses/free-courses-en.md

@@ -942,6 +942,7 @@
 * [Flask(A Python Microframework) Tutorial](http://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world)
 * [Foundations of Front End Web Development](https://www.udemy.com/course/foundations-of-front-end-development/) - Davide Molin (Udemy)
 * [Free Code Camp](https://www.freecodecamp.org)
+* [Frontend UI Development with React](https://www.youtube.com/playlist?list=PL0vfts4VzfNgUUEtEjxDVfh4iocVR3qIb) - Jeff Delaney, Fireship.io (YouTube)
 * [Full Stack Foundations](https://www.udacity.com/course/full-stack-foundations--ud088) - by AWS on Udacity
 * [Full stack open](https://fullstackopen.com/en/) - University of Helsinki, Houston Inc., Terveystalo, Elisa, K-ryhmä, Unity Technologies, Konecranes
 * [Learn web development](https://developer.mozilla.org/en-US/docs/Learn) - Mozilla Contributors