Anne Midgette: And finally, sadly, Washington National Opera’s “Ring” — the “Ring” that was more than ten years in the making, almost bankrupted the company, and ended up involving several hundred people, including three Brünnhildes who could claim to be the best singing the role today — has come to an end with the “Twilight of the Gods” on Wagner’s birthday, Sunday night, leaving many people with an acute case of “Ring” withdrawal in the weeks ahead.