docs: add plugin setup guide

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

@@ -0,0 +1,24 @@
+#pragma once
+
+#include "Scaleform/R/RefCountBase.h"
+
+namespace Scaleform::GFx
+{
+	class ASStringNode;
+
+	class __declspec(novtable) alignas(0x08) ASStringManager :
+		public RefCountBase<ASStringManager, 324>  // 00
+	{
+	public:
+		[[nodiscard]] ASStringNode* CreateStringNode(const char* a_str)
+		{
+			using func_t = decltype(&ASStringManager::CreateStringNode);
+			static REL::Relocation<func_t> func{ ID::GFx::ASStringManager::CreateStringNode };
+			return func(this, a_str);
+		}
+
+		// members
+		std::byte pad10[0xA0 - 0x10];  // 10
+	};
+	static_assert(sizeof(ASStringManager) == 0xA0);
+}