[relnote] Devtools highlights heading level

[Rumyra]

Acceptance criteria

• The listed features are documented sufficiently on MDN
• BCD is updated
• Interactive example and data repos are updated if appropriate
• The content has been reviewed as needed

For folks helping with Firefox related documentation

• Set bugs to dev-doc-complete
• Add entry to Firefox release notes for enabled/preview features
• Add/remove entry to Firefox experimental features page for preference/released features

Features to document

We should add a release note for 153 for these devtools updates as they are relevant to web devs

Related Gecko bugs

https://bugzilla.mozilla.org/show_bug.cgi?id=1588784
https://bugzilla.mozilla.org/show_bug.cgi?id=2044904

Other

• Check content open issues to see if any pertain to the subject matter. If there are any that can be closed because of the work, do so. If there are any that can be fixed relatively quickly because of the knowledge from completing this issue and you have time, feel free to go ahead and fix them.

[hamishwillee]

Status:

• Release note Ff153 devtools access heading #44758