docs: add plugin setup guide

plugin/lib/commonlibf4/include/Scaleform/M/Mutex.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "Scaleform/A/AcquireInterface.h"
+#include "Scaleform/W/Waitable.h"
+
+namespace Scaleform
+{
+	class MutexImpl;
+
+	class __declspec(novtable) Mutex :
+		public Waitable,         // 00
+		public AcquireInterface  // 18
+	{
+	public:
+		// members
+		MutexImpl* impl;  // 20
+	};
+	static_assert(sizeof(Mutex) == 0x28);
+}