“My mother was irresistible,” Maya Angelou says, but “irresistible” is also a word that many readers have applied to Angelou herself. She is a one-woman autobiography industry, as well as a poet, playwright and performer, but mostly she is a Large Public Presence. Her best-known work, “I Know Why the Caged Bird Sings,” a harrowing account of her muteness after she was raped as a child, is still widely taught.