Lionel Richie has been making music for fifty years. He has sold more than a hundred million albums, his hits too numerous to list, and he has endeared himself to younger generations as a judge on “American Idol.” He’s now the author of a memoir, “Truly.” Although the book has a lot of triumphs to cover, Richie doesn’t shy away from his failed marriages and the mistakes that led to the breakup of the Commodores, the band that launched him to stardom. “When I started out this book, I had some great stories I was gonna tell, keep it real surfacy—you know, no big deal,” Richie tells Hanif Abdurraqib. “I didn’t realize that it was going to take me on a journey of, It’s not this mountaintop and this mountaintop and this mountaintop. It was this mountaintop and then the valley. The book is about the valley. And . . . each time I went down in the valley it was painful because there were things in this book that I wanted to forget in life but what created the real substance of me was I had to face my insecurities.”