chore(html): Add minor clarification for media query example

[bsmth]

Description

I noticed we're talking about media queries on this page before we show an example without a media query.

Motivation

Clarity about the basic example without any media queries. This should help readers understand the general purpose first before applying any additional logic. It's a small, but important change for comprehension, IMO.

Related issues and pull requests

• [x] https://github.com/mdn/content/pull/39804

[github-actions[bot]]

Preview URLs

• /en-US/docs/Web/HTML/Reference/Elements/meta/name/theme-color