DEAR MISS MANNERS: I know this may sound like a silly question, but what exactly is the proper etiquette for getting on and off an elevator? Is there even a proper way? It seems that when people wait right by the door, it makes for an awkward moment when the doors open. But I, too, am guilty of waiting right at the door. GENTLE READER: Rather than telling you to back off from the entrance, or to exit according to age, gender or any other factor you can discern instantly among your fellow passengers, Miss Manners will give you a guiding principle: Do not create logjams. Therefore, do not block …