fix($markdown): Highlight kotlin code on snippets import

[kefranabg]

Summary

Fix #1831

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Docs
• Build-related changes
• Other, please describe:

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Does this PR introduce a breaking change? (check one)

• Yes
• No

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The PR fulfills these requirements:

• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

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• A convincing reason for adding this feature
• Related documents have been updated
• Related tests have been updated

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Other information:

[vue-bot]

Hey @kefranabg, thank you for your time and effort spent on this PR, contributions like yours help make Vue better for everyone. Cheers! 💚