docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/R/REGION_DATA_BASE.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "RE/R/REGION_DATA_ID.h"
+
+namespace RE
+{
+	class REGION_DATA_BASE
+	{
+	public:
+		// members
+		REGION_DATA_ID dataTypeID;  // 00
+		bool           override;    // 04
+		std::uint8_t   priority;    // 05
+	};
+	static_assert(sizeof(REGION_DATA_BASE) == 0x8);
+}