docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/B/BSResource_SDirectory2.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "RE/B/BSResource_Archive2_Index.h"
+
+namespace RE::BSResource::SDirectory2
+{
+	class Cursor :
+		public Archive2::Index::CursorWithEntry  // 000
+	{
+	public:
+		// members
+		Archive2::Index* index;  // 170
+	};
+	static_assert(sizeof(Cursor) == 0x178);
+}