docs: migrate from react router v6

Add a comprehensive migration guide from React Router v7 to TanStack
Router, addressing feedback to target the latest version.

The original PR #4704 aimed to provide a migration guide from React
Router v6. However, a comment from schiller-manuel questioned why v6 was
targeted instead of v7. This PR updates the scope to focus on React
Router v7, which was released in November 2024 and is the current
version, ensuring the guide is relevant for users migrating from the
latest React Router.

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[Open in
Web](https://cursor.com/agents?id=bc-035967dd-2396-4ba3-9226-f0bfd1c21f11)
• [Open in
Cursor](https://cursor.com/background-agent?bcId=bc-035967dd-2396-4ba3-9226-f0bfd1c21f11)

Learn more about [Background
Agents](https://docs.cursor.com/background-agent/web-and-mobile)

---------

Co-authored-by: Cursor Agent <[email protected]>

Author: tannerlinsley

docs/router/framework/react/how-to/README.md

@@ -12,6 +12,7 @@ This directory contains focused, step-by-step instructions for common TanStack R
 - [Install TanStack Router](./install.md) - Basic installation steps
 - [Deploy to Production](./deploy-to-production.md) - Deploy your app to hosting platforms
 - [Set Up Server-Side Rendering (SSR)](./setup-ssr.md) - Implement SSR with TanStack Router
+- [Migrate from React Router v7](./migrate-from-react-router.md) - Complete migration guide from React Router v7
 
 ## Using These Guides
 

docs/router/framework/react/how-to/deploy-to-production.md

@@ -432,6 +432,7 @@ Before deploying, ensure you have:
 
 After deployment, you might want to:
 
+- [Migrate from React Router v7](./migrate-from-react-router.md) - Complete migration guide if you're coming from React Router
 - [How to Set Up Server-Side Rendering (SSR)](./setup-ssr.md)
 
 <!-- TODO: Uncomment as how-to guides are created