Netflix’s new documentary about the British blues singer doesn’t dive deep into the psyche of a man who is mostly remembered for his much-mocked stage antics. But John Edginton’s film, with interviews from childhood friends, longtime bandmates, producers, engineers, admiring peers and backup singers, does create a marvelous tribute to a singer who, like James Brown, left it all onstage every night– hundreds of stages, thousands and thousands of nights . . .