docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/P/PackageList.h

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "RE/B/BSSimpleList.h"
+
+namespace RE
+{
+	class PackageList
+	{
+	public:
+		// members
+		BSSimpleList<TESPackage*> listPackages;
+	};
+	static_assert(sizeof(PackageList) == 0x10);
+}