A New York Times Book Review Editors’ Choice: There’s no right way to keep a diary, but if there’s an entertaining way, David Sedaris seems to have mas­tered it.   If it’s navel-gazing you’re after, you’ve come to the wrong place; ditto treacly self-examination. Rather, his observations turn outward: a fight between two men on a bus, a fight between two men on the street, pedestrians being whacked over the head or gathering to watch as a man considers leap­ing to his death. T