Exporting migration data from GitHub.com
To export migration data from a GitHub.com organization, you'll need to use the API to select repositories to migrate. After that, you'll generate a migration archive that you can import into a GitHub Enterprise Server instance.
Preparing the GitHub.com source organization→
Before migrating repositories from a GitHub.com organization, ensure that you have the proper authentication and administrative access.
Exporting the GitHub.com organization's repositories→
Using the Migrations API, you can export an organization's repositories. After exporting your repositories, you'll download the migration archive that's used for the import process.