Critic’s Notebook: A Generation’s Chords of Celebration, Elegy and Reckoning Resound in Two New Brit-Rock Docs

'Squaring the Circle (The Story of Hipgnosis)' and 'Have You Got It Yet? The Story of Syd Barrett and Pink Floyd' join a vibrant crop of recent documentaries that illuminate the epochal music scenes of the ’60s and ’70s.