DONETSK, Ukraine( Reuters)-About 200 protesters in separatist-controlled Donetsk confronted monitors from Europe's main security and rights watchdog on Saturday to demand the release of a pro-Russian officer captured by the Ukrainian military. The monitoring mission of the Organization for Security and Cooperation on Europe has previously faced protests organized by pro-Russian rebels, but this time protesters for the first time appeared to block the entrance to the hotel where they are based.A