CNN  —  Cher recalls a curious interlude from her rich and many-chaptered history in her new book “ Cher: The Memoir, Part One .” The Oscar- and Grammy-winner writes about how, when she went to apply to change her legal name in 1979, she was “shocked” to discover that on her birth certificate her first name was listed as Cheryl, which did not match what she thought her actual name was. “I believed Cherilyn was my name until the day years later when I decided to legally change my name to simply