Documenta tries to keep the list of artists being shown this year a secret until the fair opens. “We want to direct as much attention as possible from the list to the artworks themselves.” But “how can there be artworks to talk about without artists? The attempt has turned this Documenta into an art-world parlor game, with some dealers and critics trading guesses — and others dismissing artistic director Roger Buergel’s decision as merely an effort to create buzz.”