Fix typo in japanese article: Optimize WebFont loading and rendering

[takuyakikuchi]

Fixes: No issue created.

Changes proposed in this pull request:

• The first correction is to correct a change in meaning after translation.
• The second correction is to correct the typo.

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[chrome-devrel-review-bot]

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Requested changes

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src/site/content/ja/fast/optimize-webfont-loading/index.md

• This file passed all of our automated Markdown audits.

[chrome-devrel-review-bot]

Hello! This is an automated review by our custom reviewbot. It updates automatically when code or GitHub comments in this pull request are created or updated.

Requested changes

If there are any common problems with the content files you created or modified, they will be listed here.

src/site/content/ja/fast/optimize-webfont-loading/index.md

• This file passed all of our automated Markdown audits.