docs: add plugin setup guide

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

@@ -0,0 +1,13 @@
+#pragma once
+
+namespace RE
+{
+	namespace BSAudioUtil
+	{
+		inline std::uint16_t ClampFadeTimeSeconds(float a_seconds)
+		{
+			auto result = a_seconds * 1000;
+			return (result > 0xFFFF) ? 0xFFFF : static_cast<std::uint16_t>(a_seconds);
+		}
+	}
+}