docs: add plugin setup guide

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

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "RE/B/BSFixedString.h"
+
+namespace RE
+{
+	class TESImageSpaceModifierForm;
+
+	class ImageSpaceModifierFinder
+	{
+	public:
+		// members
+		TESImageSpaceModifierForm* modifier;        // 00
+		const BSFixedString&       modifierToFind;  // 08
+	};
+	static_assert(sizeof(ImageSpaceModifierFinder) == 0x10);
+}