This is a wiki page now.
Wiki page revisions can be seen by clicking on the orange pencil in the top right. I don’t know which users can view post revisions, but it seems that at least moderators can see them all.
Wiki pages can be edited by clicking on the cyan pencil and paper logo in the top right. It seems that you need to be at least user level 2 to be able to edit wiki posts.
And now a math formula test:
$$E = mc^2$$