ANCHORAGE, Alaska (AP) — Hundreds of barking dogs will take over downtown Anchorage on Saturday for the ceremonial start of the world’s most famous sled dog race. The event, catered to fans who hope to see and cheer on their favorite mushers, takes place a day before the competitive start. Here’s what to know about the 54th running of the Iditarod Trail Sled Dog Race, which features a new amateur category and financial support from a Norwegian billionaire. What is the Iditarod? The Iditarod was