Break up llms.txt page into multiple smaller pages

[devin-ai-integration]

Summary

Splits the single llms.txt documentation page into four focused pages under a new llms.txt navigation section:

1. Overview — What llms.txt is, generated files, custom files, page descriptions
2. Visibility tags — noindex exclusion, <llms-only>, <llms-ignore>, query parameter filtering
3. Per-page directives — Directive configuration (standalone page)
4. Analytics and integration — Dashboard analytics, adding buttons/dropdowns

Also:

• Updates navigation in docs.yml to use a section with 4 pages instead of a single page
• Adds redirect from old URL (/learn/docs/ai-features/llms-txt) to new overview page
• Updates existing redirects to point to the new overview page
• Updates ~15 files with internal links that referenced the old page or its anchors

Review & Testing Checklist for Human

• Verify the new pages render correctly in the preview deployment and content matches the original
• Check that the redirect from /learn/docs/ai-features/llms-txt to /learn/docs/ai-features/llms-txt/overview works
• Spot-check a few updated internal links (e.g., from changelogs, site-level-settings, frontmatter pages) to confirm they resolve to the correct new page and anchor

Notes

Requested by: Fern Support

Link to Devin session: https://app.devin.ai/sessions/e608c7db9ba14fdba271af67c69b94e8

[devin-ai-integration]

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[fern-api]

Requested by: devin
Slack thread: View conversation

[github-actions]

🌿 Preview your docs: https://fern-preview-fern-break-up-llms-txt-page.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/docs/ai-features/llms-txt-analytics
• learn/docs/ai-features/customize-llm-output
• learn/docs/ai-features/agent-directives
• learn/docs/ai-features/llms-txt
• learn/docs/ai-features/overview
• learn/docs/changelog/2025/11/18
• learn/docs/changelog/2026/4/2
• learn/docs/changelog/2026/4/9
• learn/docs/changelog/2026/4/10
• learn/docs/developer-tools/view-markdown
• learn/docs/configuration/site-level-settings

[github-actions]

📝 [vale] _{reported by reviewdog 🐶}
[FernStyles.Headings] 'Track LLM traffic' should use sentence-style capitalization.