css snippet: prefers-contrast: more

The prefers-contrast CSS media feature is used to detect if the user has requested that the web content is presented with a higher (or lower) contrast.

-Add to documentation: This media query only works on safari and
```
@media (prefers-contrast: more) {
}
```

Start by locating the documentation entry for the prefers-contrast CSS media feature. Add the Safari support note and the provided @media example, then verify that the documentation contains both the browser limitation and the snippet.

Written by the indexing model from the issue text.