Remove li from headings

[wbamberg]

Follow up to #12103.

https://developer.mozilla.org/en-US/docs/Web/CSS/Mozilla_Extensions#formerly_proprietary_properties_that_are_now_standard puts headings in a list, which looks silly (and is inconsistent with other bits of the same page, like https://developer.mozilla.org/en-US/docs/Web/CSS/Mozilla_Extensions#mozilla-only_properties_and_pseudo-classes_avoid_using_on_websites).

This removes them.

[github-actions]

Preview URLs

• https://pr12132.content.dev.mdn.mozit.cloud/en-US/docs/Web/CSS/Mozilla_Extensions

Flaws

URL: /en-US/docs/Web/CSS/Mozilla_Extensions
Title: Mozilla CSS extensions
on GitHub
Flaw count: 115

• macros:
  • /en-US/docs/Web/CSS/-moz-binding does not exist
  • /en-US/docs/Web/CSS/-moz-border-bottom-colors does not exist
  • /en-US/docs/Web/CSS/-moz-border-left-colors does not exist
  • /en-US/docs/Web/CSS/-moz-border-right-colors does not exist
  • /en-US/docs/Web/CSS/-moz-border-top-colors does not exist
  • and 88 more flaws omitted
• broken_links:
  • Can't resolve /en-US/docs/Mozilla/Tech/XUL
  • Can't resolve /en-US/docs/Mozilla/Gecko/Chrome/CSS
• heading_links:
  • h3 heading contains an <a> tag
  • h3 heading contains an <a> tag
  • h3 heading contains an <a> tag
  • h3 heading contains an <a> tag
  • h3 heading contains an <a> tag
  • and 15 more flaws omitted

External URLs

URL: /en-US/docs/Web/CSS/Mozilla_Extensions
Title: Mozilla CSS extensions
on GitHub

No new external URLs