Fetches the URL to download the migration archive as a tar.gz file. Depending on the resources your repository uses, the migration archive can contain JSON files with data for these objects:

• attachments
• bases
• commit_comments
• issue_comments
• issue_events
• issues
• milestones
• organizations
• projects
• protected_branches
• pull_request_reviews
• pull_requests
• releases
• repositories
• review_comments
• schema
• users

The archive will also contain an attachments directory that includes all attachment files uploaded to GitHub.com and a repositories directory that contains the repository's Git data.
Download a user migration archive