Git push/pull redirects documentation

The following discussion from gitlab-com/www-gitlab-com!8088 (comment 51878599) should be addressed:

• @marcia started a discussion: (+3 comments)

  @mydigitalself this is not the correct doc link, is it? If it is, it should be updated to reflect these changes.

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Missing docs from https://gitlab.com/gitlab-org/gitlab-ce/issues/35385.

TODOS:

• https://docs.gitlab.com/ee/user/group/index.html#transfer-an-existing-project-into-a-group should ideally be under the project's docs hierarchy. => https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/16019 and https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/3837
• Include the auto-redirects (both web and git)

Seems there are already some docs https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/15896.