docs: add plugin setup guide

plugin/lib/commonlibf4/include/Scaleform/T/ThreadId.h

@@ -0,0 +1,12 @@
+#pragma once
+
+namespace Scaleform
+{
+	using ThreadId = void*;
+
+	inline ThreadId GetCurrentThreadId()
+	{
+		return reinterpret_cast<ThreadId>(
+			static_cast<std::uintptr_t>(REX::W32::GetCurrentThreadId()));
+	}
+}