Hal Ashby directing a string of acclaimed movies in the 1970s, scoring an Oscar nom for Coming Home, but he’s largely overshadowed by the filmmaking kings of the Me Decade. Now a new documentary turns the lens on the iconoclast who also helmed such enduring pics as Harold and Maude, The Last Detail, Shampoo and Being There. Here’s the logline: Hal explores his curious historical oversight, using rare archival materials, interviews, personal letters and audio recordings…