Remove non-md compatible HTML elements in Web/HTTP

[teoli2003]

Part of #7536

This replace the HTML Elements that are cannot replaced with Markdown: <s>, <u>.

There was also an <hr> but it has been removed in a previous PR.

Note that there is no <sub>, <sup> in this area.

After this PR, I will start dealing with <table> :-) We are getting closer to be able to convert this area to Markdown!

[github-actions]

Preview URLs

• https://pr7675.content.dev.mdn.mozit.cloud/en-US/docs/Web/HTTP/Browser_detection_using_the_user_agent
• https://pr7675.content.dev.mdn.mozit.cloud/en-US/docs/Web/HTTP/Basics_of_HTTP/Choosing_between_www_and_non-www_URLs

Flaws

Note! 1 document with no flaws that don't need to be listed. 🎉

URL: /en-US/docs/Web/HTTP/Browser_detection_using_the_user_agent
Title: Browser detection using the user agent
on GitHub
Flaw count: 1

• broken_links:
  • Can't resolve /en-US/docs/Gecko_user_agent_string_reference

External URLs

URL: /en-US/docs/Web/HTTP/Browser_detection_using_the_user_agent
Title: Browser detection using the user agent
on GitHub

No new external URLs

---

URL: /en-US/docs/Web/HTTP/Basics_of_HTTP/Choosing_between_www_and_non-www_URLs
Title: Choosing between www and non-www URLs
on GitHub

No new external URLs