Add AI credits section to AI features overview page

[devin-ai-integration]

Summary

Adds a new AI credits section to the end of the AI features overview page (fern/products/docs/pages/ai/overview.mdx) with a single table of feature credit costs and inline plan allowance info:

• Feature credit costs table — Ask Fern question (2), AI examples (1), AI translation (4/page), Fern Writer session (50)
• Plan allowances (inline) — Hobby (250/mo), Pro (1,000/mo), Enterprise (Custom), with a link to the pricing page

Updates since last revision

Per feedback, consolidated from two tables into one. The per-plan credit allowances are now inline in the section intro paragraph instead of a separate table. Section moved from between "Create and update content" / "Optimize for AI" to the end of the page.

Review & Testing Checklist for Human

• Verify the credit amounts per feature (2, 1, 4, 50) are accurate and current
• Verify plan credit allowances (Hobby: 250, Pro: 1,000, Enterprise: Custom) match what's on the pricing page — these were pulled from the live site and could be stale
• Check the rendered page to confirm the table displays correctly and the end-of-page placement feels right

Recommended test plan: Use the preview deployment to view the AI features overview page and confirm table rendering, inline plan text reads naturally, and the pricing link works.

Notes

• Requested by: Fern Support
• Link to Devin run

[devin-ai-integration]

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[github-actions]

🌿 Preview your docs: https://fern-preview-a913466e-a6b9-4831-8dfa-fbb859d57be7.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/docs/ai-features/overview