When musician-singer-producer Lionel Richie was first asked to be a judge on “American Idol,” he said no. “I said, ‘Guys, I’m busy. I’m an artist. I have to be on the road. I want to be out where my fans are.’” He was where his fans were. The four-time Grammy winning performer, who also earned an Academy Award and sold over 100 million records continued to appear before adoring audiences. That was some years ago, and on Sunday Richie returns as one of three judges on ABC’s “American Idol,” as it launches its 20th year. “I got to a point in my life where you have all of this knowledge, you actu…