fix: remove incorrect folder constraint for default locale in domains

[fkatsuhiro]

Description (required)

This PR corrects the documentation regarding the folder structure for the default locale when using domains.

Related issues & labels (optional)

• Closes i18n domains folder structure is incorrect #12787
• Suggested label: implove or update documentation

[netlify]

✅ Deploy Preview for astro-docs-2 ready!

Built without sensitive environment variables

Name	Link
🔨 Latest commit	599a5f7
🔍 Latest deploy log	https://app.netlify.com/projects/astro-docs-2/deploys/6936c41587236b0008107928
😎 Deploy Preview	https://deploy-preview-12846--astro-docs-2.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[astrobot-houston]

Lunaria Status Overview

🌕 This pull request will trigger status changes.

Learn more

By default, every PR changing files present in the Lunaria configuration's files property will be considered and trigger status changes accordingly.

You can change this by adding one of the keywords present in the ignoreKeywords property in your Lunaria configuration file in the PR's title (ignoring all files) or by including a tracker directive in the merged commit's description.

Tracked Files

File	Note
en/guides/internationalization.mdx	Source changed, localizations will be marked as outdated.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.

[sarah11918]

Thank you! This fix seems to match the issue and discussion!