Removed docker_io_oauth_api.md: Docker is not currently accepting registrations for third party auth while it's determined how this will be done, if at all, in the future.

Docker-DCO-1.1-Signed-off-by: hollietealok <hollie@docker.com> (github: hollietealok)
Merge remote-tracking branch 'upstream/master' into doc_remove

Docker-DCO-1.1-Signed-off-by: hollietealok <hollie@docker.com> (github: hollietealok)
Removed OAuth doc from mkdocs.yml

Docker-DCO-1.1-Signed-off-by: hollietealok <hollie@docker.com> (github: hollietealok)
Merge pull request #7193 from hollietealok/doc_remove

Removed docker_io_oauth_api.md: Docker is not currently accepting regist...