Add revisions for articles

Most of the times when articles are updated, they are removed from the timeline. Good, but that applies to the featured ones too. Right now, there is an article about IoT, featured a while ago. Which is undergoing a moderation, but its link is provided in the top bar for featured articles. My suggestion is to add revisions to the posts. So, that until the next revision is accepted, the previous post is still available to the users. And when the next version gets published, the previous is updated and the new one takes it place.