docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/T/TLS.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "REX/W32/NT.h"
+
+namespace RE
+{
+	class TLS
+	{
+	public:
+		[[nodiscard]] static TLS* GetSingleton()
+		{
+			return *static_cast<TLS**>(REX::W32::NtCurrentTeb()->threadLocalStoragePointer);
+		}
+
+		// members
+		std::byte pad000[0x830];  // 000
+		bool      consoleMode;    // 830
+	};
+}