docs: add plugin setup guide

plugin/lib/commonlibf4/include/Scaleform/G/GFx_ASConstString.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include "Scaleform/G/GFx_ASStringNodeHolder.h"
+
+namespace Scaleform::GFx
+{
+	class ASConstString :
+		public ASStringNodeHolder
+	{
+	public:
+		const char* ToCStr() const noexcept
+		{
+			return node->data;
+		}
+	};
+	static_assert(sizeof(ASConstString) == 0x08);
+}