Github migration documentation is out-dated

[fin-ger]

Description

The documentation at

https://docs.gitea.io/en-us/faq/#how-to-migrate-from-gogs-github-etc-to-gitea

points to the deprecated gitea-github-migration tool. Instead, documentation should be provided for migrating Github repositories with the new migration form. Also, there is no hint or explanation why the Migration Items are not available when mirroring the project from Github.

Screenshots