news.scss: consolidate .ContentGroupSupplementaryArticles
news.scss: consolidate .ContentGroupSupplementaryArticles

This module is covered entirely by the default theme, except for
the white title color, which is specific for the news theme.

https://phabricator.endlessm.com/T11949

endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib,endlessm/eos-knowledge-lib