chore: use example.com as an example domains

[yoshinorin]

Summary

As is the title.

Motivation

Currently, some example docs do not use example.com.
We should use example.com for them.

refs: RFC2606

Supporting details

N/A

Related issues

N/A

Metadata

• Adds a new document
• Rewrites (or significantly expands) a document
• Fixes a typo, bug, or other error

[github-actions]

Preview URLs

• https://pr15551.content.dev.mdn.mozit.cloud/en-US/docs/Learn/CSS/CSS_layout/Grids
• https://pr15551.content.dev.mdn.mozit.cloud/en-US/docs/Learn/Server-side/First_steps/Client-Server_overview
• https://pr15551.content.dev.mdn.mozit.cloud/en-US/docs/Learn/Server-side/First_steps/Website_security
• https://pr15551.content.dev.mdn.mozit.cloud/en-US/docs/Web/API/URL_API

Flaws

Note! 3 documents with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Learn/CSS/CSS_layout/Grids
Title: Grids
on GitHub
Flaw count: 1

• broken_links:
  • Link points to the page it's already on

External URLs

URL: /en-US/docs/Learn/Server-side/First_steps/Website_security
Title: Website security
on GitHub

No new external URLs

---

URL: /en-US/docs/Learn/Server-side/First_steps/Client-Server_overview
Title: Client-Server Overview
on GitHub

No new external URLs

---

URL: /en-US/docs/Learn/CSS/CSS_layout/Grids
Title: Grids
on GitHub

No new external URLs

---

URL: /en-US/docs/Web/API/URL_API
Title: URL API
on GitHub

No new external URLs

[teoli2003]

👍

[teoli2003]

Thanks!