finalise interface & documentation

Signed-off-by: Folling <mail@folling.io>

src/folders/folder.hpp

@@ -0,0 +1,13 @@
+#pragma once
+
+#include <variant>
+
+#include <ikarus/folders/folder.h>
+
+#include <folders/blueprint_folder.hpp>
+#include <folders/entity_folder.hpp>
+#include <folders/property_folder.hpp>
+
+struct IkarusEntityFolder {
+    std::variant<IkarusBlueprintFolder, IkarusPropertyFolder, IkarusEntityFolder> data;
+};