Added youtube playlists for React and Flask (#7420)

* Added few courses in React & Flask

* New courses

* Reordered courses

* Added Flask and ReactJS Tutorials

* chore: add instructor

* fix: use titles as provided by original source

* fix: Use titles as provided by original source + Alphabetize

Co-authored-by: David Ordás <3125580+davorpa@users.noreply.github.com>

courses/free-courses-en.md

@@ -677,11 +677,12 @@
 * [React Context & Hooks Tutorial](https://www.youtube.com/playlist?list=PL4cUxeGkcC9hNokByJilPg5g9m2APUePI) - The Net Ninja
 * [React Crash Course 2020](https://www.youtube.com/watch?v=4UZrsTqkcW4) - freecodecamp
 * [React Hooks](https://www.youtube.com/playlist?list=PLZlA0Gpn_vH8EtggFGERCwMY5u5hOjf-h) - WebDevSimplified
+* [React Tutorials](https://www.youtube.com/playlist?list=PLWKjhJtqVAbkArDMazoARtNz1aMwNWmvC) - freeCodeCamp
 * [ReactJS Basics](https://www.youtube.com/playlist?list=PLe30vg_FG4OSw8SIcLVci-jB_-W1ZkLYp) - Bitfumes
 * [ReactJS Frontend Web Development For Beginners](https://www.udemy.com/course/react-tutorial/) - Ryan Dhungel (Udemy)
 * [ReactJS Full Course for Beginners \| Complete All-in-One Tutorial \| 9 Hours](https://www.youtube.com/watch?v=RVFAyFWO4go) - Dave Gray
 * [ReactJS Tutorial for Beginners](https://www.youtube.com/playlist?list=PLC3y8-rFHvwgg3vaYJgHGnModB54rxOk3) - Codevolution
-* [Start Using React to Build Web Applications](https://egghead.io/courses/react-fundamentals)
+* [Start Using React to Build Web Applications](https://egghead.io/courses/react-fundamentals) - Joe Maddalone
 
 
 #### React Native
@@ -945,6 +946,7 @@
 
 * [Flask Fridays](https://www.youtube.com/playlist?list=PLCC34OHNcOtolz2Vd9ZSeSXWc8Bq23yEz) - Codemy.com (YouTube)
 * [Flask Tutorials](https://www.youtube.com/playlist?list=PL-osiE80TeTs4UjLw5MM6OjgkjFeUxCYH) - Corey Schafer
+* [Flask Tutorials](https://www.youtube.com/playlist?list=PLzMcBGfZo4-n4vJJybUVV3Un_NFS5EOgX) - Tech with Tim
 
 
 ### QB64