docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/T/TravelMarkerStateChange.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include "RE/B/BSPointerHandle.h"
+
+namespace RE
+{
+	class MapMarkerData;
+
+	namespace TravelMarkerStateChange
+	{
+		class Event
+		{
+		public:
+			ObjectRefHandle markerRef;            // 00
+			MapMarkerData*  data;                 // 08
+			std::uint32_t   selectedMarkerIndex;  // 10
+			bool            discovered;           // 14
+		};
+		static_assert(sizeof(Event) == 0x18);
+	}
+}