tweaks echo server default error logging

examples/echo_server/echo_server.cpp

@@ -57,6 +57,9 @@ int main(int argc, char* argv[]) {
         echo_endpoint.alog().unset_level(websocketpp::log::alevel::ALL);
         echo_endpoint.elog().unset_level(websocketpp::log::elevel::ALL);
         
+        echo_endpoint.elog().set_level(websocketpp::log::elevel::ERROR);
+        echo_endpoint.elog().set_level(websocketpp::log::elevel::FATAL);
+        
         std::cout << "Starting WebSocket echo server on port " << port << std::endl;
         echo_endpoint.listen(port);
     } catch (std::exception& e) {