docs(site): add Slider and Tooltip API reference pages (#862)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

site/src/content/docs/reference/volume-slider.mdx

@@ -52,7 +52,7 @@ media-volume-slider::before {
 </FrameworkCase>
 
 <FrameworkCase frameworks={["react"]}>
-React renders a `<div>` with the same data attributes and CSS custom properties. Add a `className` and use it as the selector:
+React renders a `<div>` element. Add a `className` to style it:
 
 ```css
 .volume-slider::before {