docs(separator.mdx): fix headings levels

Author: maiieul

apps/website/src/routes/docs/headless/separator/index.mdx

@@ -14,7 +14,7 @@ A separator separates and distinguishes sections of content or groups of menuite
 
 Qwik UI's Separator implementation follows [WAI-Aria separator role requirements](https://www.w3.org/TR/wai-aria-1.2/#separator). This separator is static and should not be used for interactivity.
 
-##### ✨ Features
+## ✨ Features
 
 - Supports both horizontal and vertical orientation