feat(markdown): keep meta from fenced code block

[Qwertovsky]

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Don't drop a info from fenced code

```javascript[file.js]{4-6,7} meta-info=val
export default () => {
  console.log('Code block')
}
```

So meta-info=val will be accessible from the document tree after parsing. Property meta will be next to language, filename, highlights.
It can help to do other modifications with remark plugins, transformers, or ProseCode component.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

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[farnabaz]

LGTM 👍

[farnabaz]

@Qwertovsky do you mind fixing linter issues?

[SimonScholz]

The sample mentioned above using {4-6,7} is not targeting the sample code since it has only 3 lines.

This is really unfortunate because I am currently facing the issue that no different highlighting is applied to the lines in brackets, e.g., {4-6,7}
Shall I open a bug for this or is the {4-6,7} somehow not supported?

[nobkd]

@SimonScholz
This problem should be fixed with nuxt-modules/mdc#21. Will probably be fixed in Nuxt Content when a new version of Content gets released. It's already updated in edge channel.

Update: Fix was released with v2.8.3.