docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/B/BGSActorCellEvent.h

@@ -0,0 +1,22 @@
+#pragma once
+
+#include "RE/B/BGSActorEvent.h"
+
+namespace RE
+{
+	class BGSActorCellEvent :
+		public BGSActorEvent
+	{
+	public:
+		enum class CellFlag
+		{
+			kEnter = 0x0,
+			kLeave = 0x1
+		};
+
+		// members
+		std::uint32_t                          cellID;  // 04
+		REX::TEnumSet<CellFlag, std::uint32_t> flags;   // 08
+	};
+	static_assert(sizeof(BGSActorCellEvent) == 0xC);
+}