Add Custom Migration Services Documentation (#1816)

* Update migration-services/custom.mdx

* consolidate what to expect section

* copyedit

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Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>
Co-authored-by: Ethan Palm <[email protected]>

Author: mintlify[bot]

migration-services/custom.mdx

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+---
+title: "Custom plan migrations"
+description: "Overview of the full-service migration process, delivery timelines, and our quality assurance approach for Custom plans."
+---
+
+You can choose our migration services to transfer your documentation to Mintlify. This guide covers the migration process, delivery timelines, and our quality assurance approach.
+
+## What to expect for your migration
+
+A migration is a point-in-time transfer of your documentation that requires a code freeze. We migrate your documentation, API reference pages, branding (logos, colors, and fonts), and navigation structure. Migration services also include design or information architecture consultation and custom component development such as landing pages or custom integrations.
+
+Your migration includes a staging link to review progress and a 7-day feedback window after delivery to address any issues with content, assets, or branding.
+
+## Migration process
+
+The migration process is highly collaborative. We work closely with your team to implement custom solutions and builds that work for you!
+
+<Steps>
+<Step title="Submit the migration form">
+Submit the [migration form](https://mintlify.typeform.com/pro-migrations).
+
+Provide your documentation source, brand assets (logos, color codes, fonts), OpenAPI specs, go-live date, and preferred delivery method (GitHub PR or zip file).
+</Step>
+
+<Step title="Kick-off call">
+We review your submission and lead a kick-off call with our migration team to walk through your current setup, understand any limitations, and address any questions your team might have.
+</Step>
+
+<Step title="Receive scoping and timeline (1-2 business days)">
+We review and analyze the context from the call and provide an estimated delivery timeline within 24-48 hours. We'll flag any custom components or areas of your migration that need discussion.
+</Step>
+
+<Step title="Review progress during the migration">
+We start the migration and share a staging link so you can monitor progress in real-time.
+</Step>
+
+<Step title="Receive final delivery">
+We deliver your migration via GitHub PR or zip file based on your preference.
+</Step>
+
+<Step title="Feedback window (seven business days)">
+Submit any feedback on content, assets, or branding. We address all in-scope issues within the same timeframe.
+</Step>
+
+<Step title="Go-live support">
+We provide documentation and guidance for connecting your repository, setting up redirects, and configuring your custom domain.
+</Step>
+</Steps>
+
+## Quality assurance
+
+We work with vetted third-party vendors and conduct an internal quality audit before delivery. Here's what we check for:
+
+<Card title="Content completeness" icon="file-check">
+- All documentation from your source has been migrated.
+- Content is properly formatted with Mintlify components.
+- Navigation structure matches your specifications.
+</Card>
+
+<Card title="Visual elements" icon="palette">
+- Images and videos display correctly.
+- Custom fonts are applied throughout.
+- Light and dark mode logos are used appropriately.
+- Color schemes meet contrast requirements in both modes.
+</Card>
+
+<Card title="Functionality" icon="rocket">
+- All links work correctly (no broken links).
+- Table of contents renders properly.
+- React components function as expected.
+- No performance issues.
+</Card>
+
+## After your migration
+
+Once we deliver your migration, you'll need to complete the following steps to launch your documentation:
+
+1. [Connect your GitHub repository and get setup](/quickstart#install-the-github-app).
+2. [Set up redirects, if required](/create/redirects).
+3. [Configure your custom domain](/customize/custom-domain).
+4. **Test before going live** - Before switching over from your old documentation:
+   - Review all pages on your staging link.
+   - Test navigation and search functionality.
+   - Verify all images and videos load correctly.
+   - Check that code blocks render properly.
+   - Test on mobile and desktop.
+5. **Launch!** Your documentation is ready to go live!
+
+<Note>
+**Need help?** Our migration team is available to guide you through these steps. Reach out via your dedicated Slack channel or [[email protected]](mailto:[email protected]).
+</Note>
+
+## Frequently asked questions
+
+<AccordionGroup>
+<Accordion title="How long does a migration take?">
+We typically deliver migrations within 2-6 weeks, depending on complexity. You'll receive a specific timeline after the kick-off call.
+</Accordion>
+
+<Accordion title="Can I request changes after delivery?">
+Yes. You have a 7-day feedback window after delivery to request changes to content, assets, or branding. We address all in-scope feedback within the same timeframe and work with you right until you are ready to go live.
+</Accordion>
+
+<Accordion title="What do I need to do after the migration is complete?">
+The migration transfers your content, but you'll need to:
+- Connect your documentation repository to your Mintlify dashboard.
+- Set up redirects from your old documentation URLs.
+- Configure your custom domain.
+
+We provide step-by-step documentation and support for each of these steps.
+</Accordion>
+
+<Accordion title="Can I customize the navigation structure?">
+Yes. You can provide a custom information architecture and we will implement it. We also work with you on custom component development if that is needed and supported by the platform.
+</Accordion>
+
+<Accordion title="What happens if my documentation changes during the migration?">
+Since migrations require a code freeze, any changes made to your source documentation after submission won't be included. We recommend completing all updates before starting the migration.
+
+If this is not possible, our team will work with you to set short sprints to migrate certain sections or reserve dedicated time post the first sprint to migrate the delta changes made during the migration.
+</Accordion>
+</AccordionGroup>