Ensure most demos have descriptions and screenshots

loading/autoload/README.md

@@ -7,3 +7,7 @@ Language: GDScript
 Renderer: GLES 2
 
 Check out this demo on the asset library: https://godotengine.org/asset-library/asset/529
+
+## Screenshots
+
+![Screenshot](screenshots/autoload.png)

loading/scene_changer/README.md

@@ -7,3 +7,7 @@ Language: GDScript
 Renderer: GLES 2
 
 Check out this demo on the asset library: https://godotengine.org/asset-library/asset/531
+
+## Screenshots
+
+![Screenshot](screenshots/scene_changer.png)

loading/serialization/project.godot

@@ -11,6 +11,11 @@ config_version=4
 [application]
 
 config/name="Saving and Loading (Serialization)"
+config/description="This demo showcases how to save a simple game with each serialization
+format supported by Godot: ConfigFile and JSON.
+
+For more information, see this documentation article:
+https://docs.godotengine.org/en/latest/tutorials/io/saving_games.html"
 run/main_scene="res://save_load.tscn"
 config/icon="res://icon.png"