docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/S/SCRIPT_LOCAL.h

@@ -0,0 +1,14 @@
+#pragma once
+
+namespace RE
+{
+	class SCRIPT_LOCAL
+	{
+	public:
+		// members
+		std::uint32_t id;         // 0
+		float         value;      // 4
+		bool          isInteger;  // 8
+	};
+	static_assert(sizeof(SCRIPT_LOCAL) == 0xC);
+}