Just a short stroll from the famous track at Churchill Downs, where he rode to four victories in the Kentucky Derby, some of Bill Shoemaker’s most treasured items are on display for racing fans making a pilgrimage to the famous racetrack. The special exhibit — titled “Shoemaker: Start to Finish” — opened Monday at the Kentucky Derby Museum and carries visitors down memory lane, spanning the 40-plus-year career of a pint-sized man who became a giant in thoroughbred racing history.