Add link and intro to Godot design philosophy page, update toc

getting_started/step_by_step/godot_design_philosophy.rst

@@ -1,6 +1,8 @@
 Godot’s design philosophy
 =========================
 
+*Now you've gotten your hands wet, let's talk about Godot's design.*
+
 **Every game engine is different and fits different needs**. They do not
 only offer a wide range of features: each engine’s design is unique. This
 leads to different workflows and different ways to reason about your
@@ -12,6 +14,8 @@ an engine comparison. To know whether any engine can be a good fit for
 your project or not, you need to both try it out for yourself and
 understand its design and limitations.
 
+Please watch `Discover Godot 3, the Free game engine <https://youtu.be/4v3qge-3CqQ>`_ if you're looking for an overview of the engine's features.
+
 Object-oriented design and composition
 --------------------------------------
 
@@ -92,7 +96,7 @@ Note that if this is true for 2d at the time of writing, the 3d
 workspace still doesn’t feature as many tools. You’ll need external
 programs or add-ons to edit terrains, animate complex characters, etc.
 Godot provides a complete API to extend the editor’s functionality using
-game code. See `The Godot editor is a Godot game <#>`__ below.
+game code. See `The Godot editor is a Godot game`_ below.
 
 |image4|
 

getting_started/step_by_step/index.rst

@@ -5,13 +5,14 @@ Step by step
    :maxdepth: 1
    :name: toc-learn-step_by_step
 
+   intro_to_the_editor_interface
    scenes_and_nodes
    instancing
    instancing_continued
    scripting
    scripting_continued
-   intro_to_the_editor_interface
    your_first_game
+   godot_design_philosophy
    ui_introduction_to_the_ui_system
    ui_main_menu
    ui_game_user_interface