Four decades ago, Lionel Richie and Michael Jackson teamed up to write a charity song to raise funds to fight famine in Africa – and they got the biggest stars of the music world in the same room with producer Quincy Jones to record it. Richie talks with correspondent Tracy Smith about the making of “We Are the World,” and how – following the new Netflix documentary, “The Greatest Night in Pop” – the song is back on the charts, continuing to raise millions for those in need.