Laura Poitras announces early in her Julian Assange documentary “Risk”: “This is not the film I thought I was making.” “I thought I could ignore the contradictions,” the Oscar-winning “Citizenfour” filmmaker says in a voiceover. “I thought they were not part of the story. I was so wrong. They are becoming the story.” Decoding “the story” when it comes to the WikiLeaks founder has never been easy. It’s evolving even now, just as Poitras’ six-years-in-the-making documentary — one made with rare access to an explosively controversial figure under ever-increasing international pressure — is hitting theaters.