When Ksenia Coffman started editing [Wikipedia] , she was like a tourist in Buenos Aires in the 1950s. She came to learn the tango, admire the architecture, sip maté. She didn’t know there was a Nazi problem. But Coffman, who was born in Soviet-era [Russia] and lives in Silicon Valley, is an intensely observant traveler. As she link-hopped through articles about the Second World War, one of her favorite subjects, she saw what seemed like a concerted effort to look the other way about Germany’s wartime atrocities. Coffman can’t recall exactly when her concern set in. Maybe it was when...