Fix curl command formatting in sample-data.md

[gingerwizard]

Summary

Fixes load command

Checklist

• Delete items not relevant to your PR
• URL changes should add a redirect to the old URL via https://github.com/ClickHouse/clickhouse-docs/blob/main/docusaurus.config.js
• If adding a new integration page, also add an entry to the integrations list here: https://github.com/ClickHouse/clickhouse-docs/blob/main/docs/integrations/index.mdx

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Project	Deployment	Preview	Comments	Updated (UTC)
clickhouse-docs	Ready	Preview	Comment	Oct 26, 2025 0:42am
clickhouse-docs-jp	Building	Preview	Comment	Oct 26, 2025 0:42am

2 Skipped Deployments

Project	Deployment	Preview	Comments	Updated (UTC)
clickhouse-docs-ru	Ignored	Preview		Oct 26, 2025 0:42am
clickhouse-docs-zh	Ignored	Preview		Oct 26, 2025 0:42am