Components: Add CHANGELOG entry for the fieldset removal from FontAppearanceControl

[ciampo]

Description

Small follow-up of #35461 adding a CHANGELOG entry

How has this been tested?

This PR doesn't introduce any runtime changes.

Types of changes

Docs update (CHANGELOG)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

[mirka]

Thanks for this! Should we put it under an ### Experimental heading since this is still in the experimental stage?

gutenberg/packages/block-editor/src/components/index.js

Line 45 in 5b54f87

export { default as __experimentalFontAppearanceControl } from './font-appearance-control';

[ciampo]

Absolutely, the lack of a README made me skip the check to see if this component is experimental. Thank you for catching this!