Document api:apiName link syntax for API Reference sections

[devin-ai-integration]

Summary

Documents the new api:apiName MDX link syntax added in fern-platform#9726, which allows docs authors to link to the root of an API Reference section (not just individual endpoints).

Changes:

• fern/snippets/api-link-syntax.mdx: Broadened the shared snippet to cover both endpoint links (api:METHOD/path) and the new section links (api:apiName), with an example and rendered preview.
• Heading renames in markdown-basics.mdx and api-ref-content.mdx: Updated section headings from "Link to an API endpoint" / "Linking to API endpoints" → "API link syntax" since the snippet now covers both link types.
• Changelog entry (2026-04-14.mdx): Appended a Docs changelog entry for the new feature (merged with the existing AI search model update entry for the same date).

Review & Testing Checklist for Human

• Broken anchor links from heading renames: The headings changed from ### Link to an API endpoint → ### API link syntax (in markdown-basics.mdx) and ## Linking to API endpoints → ## API link syntax (in api-ref-content.mdx). Check whether any other pages or external resources link to the old anchors (#link-to-an-api-endpoint, #linking-to-api-endpoints). Consider adding redirects if needed.
• Verify the changelog "Read the docs" button resolves correctly: it points to /learn/docs/writing-content/markdown-basics#api-link-syntax, which depends on the new heading slug.
• Preview the rendered snippet on both pages where it's included (markdown-basics and api-ref-content) to confirm the new section reads well in context.

Notes

• The api:plant-store example in the snippet is a placeholder following the plant-themed content convention. It won't resolve to a real link on the docs site, but it appears only inside a code block and a highlight-frame demo.
• Vale passes with 0 errors and 0 warnings. The single remaining suggestion (in addition → also) was left as-is for readability.

Link to Devin session: https://app.devin.ai/sessions/9f5fa9caeb794b968d1e83c7644308c3
Requested by: @kafkas

[devin-ai-integration]

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[github-actions]

📝 [vale] _{reported by reviewdog 🐶}
[Microsoft.Wordiness] Consider using 'also' instead of 'in addition'.

[github-actions]

🌿 Preview your docs: https://fern-preview-devin-1776194577-document-api-apiname-links.docs.buildwithfern.com/learn

Here are the markdown pages you've updated:

• learn/docs/api-references/write-markdown-in-api-reference
• learn/docs/changelog/2026/4/14
• learn/docs/writing-content/markdown-basics