docs(themes): update Preloading Fonts section

[amjadorfali]

• use css property font-face: swap instead of preloading the font to not block rendering

Linked Issue

Closes #2835

Description

Following the previously recommended guide to Preload fonts makes the font loading event block the rendering of the website and heavily affect LCP. Removing it and using the CSS property font-face to handle events on font loading leads to no flickering, and doesn't affect LCP.

Changsets

Instructions: Changesets automate our changelog. If you modify files in /packages, run pnpm changeset in the root of the monorepo, follow the prompts, then commit the markdown file. Changes that add features should be minor while chores and bugfixes should be patch. Please prefix the changeset message with feat:, bugfix: or chore:.

Checklist

Please read and apply all contribution requirements.

• This PR targets the dev branch (NEVER master)
• Documentation reflects all relevant changes
• Branch is prefixed with: docs/, feat/, chore/, bugfix/
• Ensure Svelte and Typescript linting is current - run pnpm ci:check
• Ensure Prettier linting is current - run pnpm format
• All test cases are passing - run pnpm test
• Includes a changeset (if relevant; see above)

[changeset-bot]

⚠️ No Changeset found

Latest commit: d8f5dd7

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
skeleton-docs	✅ Ready (Inspect)	Visit Preview	Aug 23, 2024 6:07pm

[vercel]

@amjadorfali is attempting to deploy a commit to the Skeleton Labs Team on Vercel.

A member of the Team first needs to authorize it.

[endigo9740]

Thanks @amjadorfali - just a couple small changes needed. Once those are in place I'm happy to merge. Thanks!

[amjadorfali]

@endigo9740 Thanks for the feedback. I resolved your comments