Add Processing Resource - Fix (#4340)

* Add Python 3 Book

Python 3 book from DigitalOcean.

* Update list to add learning Processing resource

Reattempted.

* Update podcasts-screencasts-en.md

Changed playlist and added the contributor name.

* Alphabetize Processing playlists

Alphabetize the processing playlists added.

* Removed Processing Resource

Removed Processing YouTube links from screencasts.

* Updated free-courses with Processing Resource

Added processing resource in free courses list.

free-courses-en.md

@@ -472,6 +472,11 @@
 * [PHP Tutorial](https://www.w3schools.com/php) - W3Schools
 
 
+### Processing
+
+* [Learning Processing: A Beginner's Guide to Programming Images, Animation, and Interaction](https://www.youtube.com/c/TheCodingTrain/playlists?view=50&sort=dd&shelf_id=10) - The Coding Train
+
+
 ### Python
 
 * [An Introduction to Interactive Programming in Python (Part 1)](https://www.coursera.org/learn/interactive-python-1) (Coursera)