Junot Díaz says children’s books lack diversity. He hopes his will help change that.

Twenty years ago, novelist Junot Díaz promised his goddaughters he would write a children’s book for them. Their request: to see people like them — Dominican girls living in the Bronx — in its pages.The girls are no longer girls but their book is finally here. On Tuesday, Díaz, best known for his Pulitzer Prize-winning novel “The Brief Wondrous Life of Oscar Wao,” published “Islandborn.” As promised, it is a picture book that features Domin