Update reference.mdx

Author: Qianqianye

src/content/pages/en/reference.mdx

@@ -9,4 +9,4 @@ sticks out 75px from the header. This is a little hack to push everything down
 by that much so nothing gets cut off. */}
 <div class="h-[75px]" />
 
-Looking for p5.sound? Go to the <a href="https://archive.p5js.org/reference/#/libraries/p5.sound">p5.sound reference!</a>
+Looking for p5.sound? Go to the <a href="https://archive.p5js.org/reference/#/libraries/p5.sound">p5.sound reference</a>!