Update DNS request explanation in documentation

[securitypedant]

Clarified the DNS resolution process by specifying that the user's client receives an address based on the DNS resolution from Cloudflare's 1.1.1.1 servers or can use a Resolver Policy to redirect DNS requests.

Summary

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.