docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/D/DisconnectHandler.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "RE/B/BSInputEventUser.h"
+
+namespace RE
+{
+	class __declspec(novtable) DisconnectHandler :
+		public BSInputEventUser
+	{
+	public:
+		static constexpr auto RTTI{ RTTI::DisconnectHandler };
+		static constexpr auto VTABLE{ VTABLE::DisconnectHandler };
+	};
+	static_assert(sizeof(DisconnectHandler) == 0x10);
+}