Add search for knowledge-base articles

[Blargian]

Summary

Adds a simple search to filter KB articles by title. Closes #3125

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/en/integrations/index.mdx