The UI has changed but the functionality largely remains the same. To add users, admin or otherwise, using the "Administrator / Developer" drop down in the top left. Then Developer -> Project -> Project Access. Add users with @github after their name like jane@github.
You can also add users via the commandline: oc policy add-role-to-user <role> <user> for a given namespace. This will create a rolebinding in that namespace just like the above gif.
The UI has changed but the functionality largely remains the same. To add users, admin or otherwise, using the "Administrator / Developer" drop down in the top left. Then Developer -> Project -> Project Access. Add users with
@github
after their name likejane@github
.