Suggestion: Change headline from "Bootstrap 4.0 includes a powerful mobile-first flexbox grid system" to "Bootstrap v4a6 uses flexbox by default". I feel this

Suggestion: Change headline from "Bootstrap 4.0 includes a powerful mobile-first flexbox grid system" to "Bootstrap v4a6 uses flexbox by default". I feel this much better conveys the meaningful change that HN is discussing here and that's otherwise not mentioned clearly on the current link to the docs (vs the blog post linked by another user below).