docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/N/NiFrustumPlanes.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include "RE/N/NiPlane.h"
+
+namespace RE
+{
+	class NiFrustumPlanes
+	{
+	public:
+		enum class Plane
+		{
+			kNearPlane = 0x0,
+			kFarPlane = 0x1,
+			kLeftPlane = 0x2,
+			kRightPlane = 0x3,
+			kTopPlane = 0x4,
+			kBottomPlane = 0x5
+		};
+
+		// members
+		NiPlane       cullingPlanes[6];  // 00
+		std::uint32_t activePlanes;      // 60
+		std::uint32_t basePlaneStates;   //64
+		std::byte     pad[0x8];          // 68
+	};
+	static_assert(sizeof(NiFrustumPlanes) == 0x70);
+}