DOCUMENTARY SPECIAL: Yesterday on ABC’s American Idol, former Idol contestant Adam Lambert was seen mentoring singers on that long-running singing competition show. Tonight he’s the focus of an ABC documentary, charting Lambert’s rise from Idol hopeful to Freddie Mercury’s replacement as lead vocalist for Queen. People seen in tonight’s documentary include original Idol judge Simon Cowell and actor Rami Malek, who portrayed Mercury, and won an Oscar for it, in the Mercury film biography Bohemian Rhapsody. This week, American Idol winner Kelly Clarkson hosts NBC’s coverage of the 2019 Billboard award, and Idol deserves its strong measure of praise. Clarkson as the winner, and even such prominent finalists and other non-winners as Jennifer Hudson and Lambert himself, have become much more famous, and accomplished, than any of the winners to date on, say, NBC’s The Voice…