revert: rewrite help summary New users have a tendency to mistake 'revert' as the command to use to check out old revisions. They also occasionally mistake revert for a generalized undo (compare rollback). This version intentionally aims to avoid mentioning 'earlier' and thus intentionally no longer alludes to the (secondary) -r behavior (which in fact is not actually limited to 'earlier'). Instead, we mention checkout state, to convey that we can restore things to the way they were when checked out.