docs: add plugin setup guide

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

@@ -0,0 +1,13 @@
+#pragma once
+
+#include "RE/I/InventoryUserUIInterface.h"
+
+namespace RE
+{
+	class __declspec(novtable) BarterMenuTentativeInventoryUIInterface :
+		public InventoryUserUIInterface  // 00
+	{
+	public:
+	};
+	static_assert(sizeof(BarterMenuTentativeInventoryUIInterface) == 0x80);
+}