feat: add initial People Playground mod development kit

extracted_wiki_content/snippets/creating_a_background_script.txt

@@ -0,0 +1,31 @@
+URL: https://wiki.studiominus.nl/snippets/backgroundScriptCreation.html
+Title: People Playground Modding - Creating a background script
+==================================================
+
+Creating a background script
+This code snippet shows how to create a background script.
+using UnityEngine;
+
+namespace Mod
+{
+    public class Mod
+    {
+        public static void Main()
+        {
+            //tell the game that a component of this type should be created in the background
+            ModAPI.Register<CoolBackgroundScriptTime>();
+        }
+    }
+
+    //define a behaviour that will run in the background
+    //it will be attached to an otherwise empty gameobject floating in the scene, created when the catalog is first populated
+    public class CoolBackgroundScriptTime : MonoBehaviour
+    {
+        //treat it like any other component
+        void Update()
+        {
+            if (Input.GetKey(KeyCode.P))
+                ModAPI.Notify("gamer is holding the P key");
+        }
+    }
+}