docs: add plugin setup guide

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

@@ -0,0 +1,17 @@
+#pragma once
+
+namespace RE
+{
+	class BGSDualCastDataDEF
+	{
+	public:
+		// members
+		BGSProjectile*    projectile;     // 00
+		BGSExplosion*     explosion;      // 08
+		TESEffectShader*  effectShader;   // 10
+		BGSArtObject*     hitEffectArt;   // 18
+		BGSImpactDataSet* impactDataSet;  // 20
+		std::uint32_t     flags;          // 28
+	};
+	static_assert(sizeof(BGSDualCastDataDEF) == 0x30);
+}