Social: Include developer blog tutorial in README

[Mamaduka]

What?

This is a follow-up to #70961.

PR adds a link to the developer blog tutorial for adding custom social icons to the editor - https://developer.wordpress.org/news/2025/08/registering-custom-social-icons-in-wordpress-6-9/.

Testing Instructions

None.

[Copilot]

Pull Request Overview

This PR enhances the Social Link block documentation by adding a reference to the developer blog tutorial for custom social icons. The change improves developer resources by providing both the original implementation ticket and a comprehensive tutorial guide.

Key changes:

• Restructures the custom social icons section to include multiple resources
• Adds a link to the WordPress developer blog tutorial for registering custom social icons

Comments suppressed due to low confidence (1)

packages/block-library/src/social-link/README.md:21

• WordPress 6.9 may not exist yet. My knowledge cutoff is January 2025, and it's currently August 2025, so this version may have been released since then, but please verify that WordPress 6.9 is a valid, released version.

Starting from WordPress 6.9, it's possible to add custom social icons to your site. See:

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[github-actions]

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Co-authored-by: Mamaduka <[email protected]>
Co-authored-by: bph <[email protected]>

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[github-actions]

Flaky tests detected in bd77672.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/17092119806
📝 Reported issues:

• [Flaky Test] should only consider the content as one tab stop #41396 in /test/e2e/specs/editor/various/writing-flow.spec.js
• [Flaky Test] should refresh the page when stylesheet loading fails #71135 in /test/e2e/specs/interactivity/router-styles.spec.ts

[bph]

LGTM :-)