docs: add post-migration steps for updating original repository

[Copilot]

The CONTRIBUTING.md migration guide was incomplete—it didn't document what to do with the original repository after successfully migrating a plugin to the monorepo.

Changes

Added Step 5: Update the original repository to the migration section with:

• README update template - Markdown snippet to notify users the plugin moved, where to find it, and where to file issues
• Issue migration step - Required step to review, label, and migrate existing issues to the monorepo before archiving
• Repository archiving - Required step to archive the original repo to prevent new issues/PRs while preserving history
• Example reference - Links to document-internationalization PR chore(format): 🤖 ✨ #214 showing this pattern in practice

Example

The README template added to the guide:

> **Note:** This repository has been moved to the [sanity-io/plugins](https://github.com/sanity-io/plugins) monorepo.
>
> All future development, issues, and releases will be managed there.
>
> - New location: `plugins/PLUGIN-NAME` (e.g., `plugins/@sanity/document-internationalization`)
> - npm package: The package name remains the same
> - Issues: Please open new issues in the [monorepo](https://github.com/sanity-io/plugins/issues)

This completes the migration workflow by documenting how to properly communicate the move to plugin users and ensure existing issues are preserved in the monorepo.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
plugins-studio	Ready	Preview, Comment	Feb 17, 2026 7:44am

[changeset-bot]

⚠️ No Changeset found

Latest commit: 50eec4f

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[Copilot]

Pull request overview

This PR adds comprehensive post-migration documentation to the CONTRIBUTING.md file, filling a gap in the migration guide by documenting what to do with the original repository after successfully migrating a plugin to the monorepo.

Changes:

• Added a new "Step 5: Update the original repository" section to the migration workflow
• Included a README update template with clear migration notice and navigation instructions
• Added steps for migrating existing issues to the monorepo before archiving
• Documented the repository archiving process to prevent new issues/PRs while preserving history

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.