Fx152: Update experimental features release note for JPEG XL support

[dipikabh]

Description

JPEG XL has been enabled by default in Nightly and available behind pref in Fx152 beta and release.

This PR is based on the work contributed by @jacob-willden in #44205, which updated the "JPEG XL support" section in Experimental features page.

This PR also adds the "better compression" phrasing suggested in the bugzilla comment.

Related issues and pull requests

Doc issue: #44418
BCD update: mdn/browser-compat-data#29852

[github-actions]

Preview URLs (1 page)

• /en-US/docs/Mozilla/Firefox/Experimental_features

External URLs (3)

URL: /en-US/docs/Mozilla/Firefox/Experimental_features
Title: Experimental features in Firefox

• https://bugzil.la/1539075 (1 time) (Note! This may be a new URL 👀)
• https://bugzil.la/2016688 (1 time) (Note! This may be a new URL 👀)
• https://jpeg.org/jpegxl/ (2 times) (Note! This may be a new URL 👀)

(comment last updated: 2026-06-15 21:45:38)

[pepelsbey]

Looks good! Thank you 🙂

I would only suggest updating the JPEG XL pitch to avoid comparison with others.

Approving for the ease of merging