docs: add cross-reference to Blueprints contribution process

[luke6Lh43]

Description

Adds a cross-reference from the Blueprints and Reference Implementations guidance page to the full contribution process now documented in the sig-end-user repository.

Previously, the "How to contribute" section explained how to raise a proposal issue but did not describe what happens afterwards. This could lead contributors to open a documentation pull request against this repository before their proposal has been reviewed and approved by the Blueprints Team.

This change adds a callout clarifying that contributors should submit a proposal issue first in the End User SIG Repository and wait for approval before opening a documentation PR here. It links to the step-by-step contribution workflow in sig-end-user, which covers the journey from proposal to publication.

Related

• Issue: Improve documentation for Blueprint and Reference Implementation contributions sig-end-user#359
• Companion PR: docs: add Blueprint and Reference Implementation contribution process sig-end-user#374

Changes

• Added a callout in the "How to contribute" section clarifying the proposal-first workflow
• Linked to the Blueprints and Reference Implementations contribution process in sig-end-user

---

• I have read and followed the Contributing docs, especially the "First-time contributing?" section.
• This PR has content that I did not fully write myself.
  • I used AI and I have read and followed the Generative AI Contribution Policy.
• I have the experience and knowledge necessary to understand, review, and validate all content in this PR.¹

Footnotes

1. Yes, I can answer maintainer questions about the content of this PR, without using AI. ↩

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Status last refreshed: 2026-07-25 20:54:39 UTC.

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