v4: question should media query mixin be nested or not?

Created by: bassjobsen

not nested: https://github.com/twbs/bootstrap/blob/v4-dev/scss/_jumbotron.scss#L12 nested: https://github.com/twbs/bootstrap/blob/v4-dev/scss/_navbar.scss#L11

related: https://github.com/twbs/bootstrap/pull/18258