docs: add plugin setup guide

plugin/lib/commonlibf4/include/RE/G/GrassParam.h

@@ -0,0 +1,22 @@
+#pragma once
+
+namespace RE
+{
+	class GrassParam
+	{
+	public:
+		// members
+		const char*   geomFilename;     // 00
+		std::uint32_t grassID;          // 08
+		float         positionRange;    // 0C
+		float         heightRange;      // 10
+		float         colorRange;       // 14
+		float         waveOffsetRange;  // 18
+		float         wavePeriod;       // 1C
+		bool          vertexLighting;   // 20
+		bool          uniformScaling;   // 21
+		bool          fitToSlope;       // 22
+		bool          wind;             // 23
+	};
+	static_assert(sizeof(GrassParam) == 0x28);
+}