Fixes #17969: Clear horizontal dls

- Using the grid classes, they still need clearfixes since rows aren't injected between them all
- Update docs to fix broken classes

scss/_type.scss

@@ -137,3 +137,12 @@ mark,
     content: "\00A0 \2014"; // nbsp, em dash
   }
 }
+
+// Clean up some horizontal `<dl>`s built with grids
+// scss-lint:disable QualifyingElement
+dl.row {
+  > dd + dt {
+    clear: left;
+  }
+}
+// scss-lint:enable QualifyingElement