docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/I/ImageSpaceData.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include "RE/I/ImageSpaceBaseData.h"
+#include "RE/I/ImageSpaceModData.h"
+
+namespace RE
+{
+	class ImageSpaceData
+	{
+	public:
+		// members
+		ImageSpaceBaseData baseData;           //00
+		ImageSpaceModData  modData;            //58
+		float              highestTintAmount;  //A8
+		float              highestFadeAmount;  //AC
+	};
+	static_assert(sizeof(ImageSpaceData) == 0xB0);
+}