Replace Harvard course recommendation with Learn GDScript from Zero

This resource didn't exist back when the Harvard course was added
as a recommendation in 2020. It's much easier to follow
(shorter, uses less technical terms) and is arguably more motivating
for newcomers.

Author: Calinou

getting_started/introduction/introduction_to_godot.rst

@@ -111,10 +111,11 @@ how to think like a programmer first.
 Godot relies on the object-oriented programming paradigm. Being comfortable with
 concepts such as classes and objects will help you code efficiently in it.
 
-If you are entirely new to programming, we recommend following the `CS50 open
-courseware`_ from Harvard University. It's a great free course that will teach
-you everything you need to know to be off to a good start. It will save you
-countless hours and hurdles learning any game engine afterward.
+If you are entirely new to programming, GDQuest's *Learn GDScript From Zero*
+is a free and open source interactive tutorial for absolute beginners to
+learn to program with Godot's GDScript language. It is available as a
+`desktop application <https://gdquest.itch.io/learn-godot-gdscript>`_
+ or `in the browser <https://gdquest.github.io/learn-gdscript>`_.
 
 .. note:: In CS50, you will learn multiple programming languages. Don't be
           afraid of that: programming languages have many similarities. The

getting_started/introduction/learning_new_features.rst

@@ -66,12 +66,11 @@ Teaching programming foundations and how to think like a game developer is
 beyond the scope of Godot's documentation. If you're new to programming, we
 recommend two excellent free resources to get you started:
 
-1. Harvard university offers a free courseware to learn to program, `CS50
-   <https://cs50.harvard.edu/x/>`_. It will teach you programming
-   fundamentals, how code works, and how to think like a programmer. These
-   skills are essential to become a game developer and learn any game engine
-   efficiently. You can see this course as an investment that will save you time
-   and trouble when you learn to create games.
+1. GDQuest's *Learn GDScript From Zero* is a free and open source
+   interactive tutorial for absolute beginners to learn to program
+   with Godot's GDScript language. It is available as a
+   `desktop application <https://gdquest.itch.io/learn-godot-gdscript>`_
+   or `in the browser <https://gdquest.github.io/learn-gdscript>`_.
 
 2. If you prefer books, check out the free ebook `Automate The Boring Stuff With
    Python <https://automatetheboringstuff.com/>`_ by Al Sweigart.