feat: add initial People Playground mod development kit

extracted_wiki_content/snippets/registering_an_item.txt

@@ -0,0 +1,22 @@
+URL: https://wiki.studiominus.nl/snippets/registerItem.html
+Title: People Playground Modding - Registering an item
+==================================================
+
+Registering an item
+This code snippet shows a simple template of a ModAPI.Register call.
+// register item to the mod api
+ModAPI.Register(
+    new Modification()
+    {
+        OriginalItem = ModAPI.FindSpawnable("Knife"), //item to derive from
+        NameOverride = "Dagger -MoreMelee", //new item name with a suffix to assure it is globally unique
+        DescriptionOverride = "It is a dagger.", //new item description
+        CategoryOverride = ModAPI.FindCategory("Melee"), //new item category
+        ThumbnailOverride = ModAPI.LoadSprite("daggerView.png"), //new item thumbnail (relative path)
+        AfterSpawn = (Instance) => //all code in the AfterSpawn delegate will be executed when the item is spawned
+        {
+            //get the SpriteRenderer and replace its sprite with a custom one
+            Instance.GetComponent<SpriteRenderer>().sprite = ModAPI.LoadSprite("dagger.png"); 
+        }
+    }
+);