Issue #2864305 by maikelkoopman: document atoms in styleguide

assets/css/alert.css

assets/css/badge.css

assets/css/badges.css

assets/css/base.css

assets/css/button.css

assets/css/cards.css

assets/css/dropdown.css

assets/css/form-elements.css

assets/css/kss.css

assets/css/labels.css

assets/css/like.css

assets/css/list-group.css

assets/css/list.css

assets/css/navbar.css

assets/css/styleguide.css

assets/css/toc.css

components/00-config/_mixins.scss

components/00-config/_variables.scss

components/00-config/mixins/_alert.scss

components/00-config/mixins/_badge.scss