Add postgres cdc guide to doc

[lio-p]

Summary

Port the Postgres CDC blog to documentation

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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Name	Status	Preview	Comments	Updated (UTC)
clickhouse-docs	✅ Ready (Inspect)	Visit Preview		Apr 10, 2025 4:44pm

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[gingerwizard]

@lio-p i thought the plan was to update https://clickhouse.com/docs/migrations/postgres/migrations/postgresql