Improve formatting of /en/integrations/javascript

[Blargian]

Summary

Formatting fixes to /docs/en/integrations/javascript

• Tabulate the config settings lists
• Add experimental badges
• Use correct syntax for footnotes
• Fix a heading which is the wrong size

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