docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/E/EffectItemData.h

@@ -0,0 +1,14 @@
+#pragma once
+
+namespace RE
+{
+	class EffectItemData
+	{
+	public:
+		// members
+		float        magnitude;  // 0
+		std::int32_t area;       // 4
+		std::int32_t duration;   // 8
+	};
+	static_assert(sizeof(EffectItemData) == 0xC);
+}