The second season of Alena Smith’s “Dickinson” begins with a warning and provocation. “The records of Emily Dickinson’s life, up to and including Sue and Austin’s marriage, are full and factual compared with what lies ahead,” says narrator, star, and executive producer Hailee Steinfeld, an admission that yes, the first season took liberties with history, but this one will make those liberties look factual by contrast. Neither Smith, Steinfeld, nor the writers’ room have a choice if the story of Dickinson’s arc from no one of note to one of America’s most celebrated and enduring poets is to continue. Buckle up.