“In the last 35 years, Twyla Tharp has created 126 dances, choreographed 5 movies (including Milos Forman’s “Hair” and “Amadeus”), won two Emmys for her television special “Baryshnikov by Tharp,” written an autobiography, worked on four Broadway shows and, this year, won a Tony for “Movin’ Out,” a narrative ballet set to Billy Joel’s music. Now she has completed her second book, “The Creative Habit.” And she wants to be very clear that it is not about dance.