correct spelling of 'principal'

[fooyay]

Summary

Correct spelling of 'principal'

Checklist

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

[CLAassistant]

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