correcting typo

src/users/broker.cpp

@@ -72,7 +72,7 @@ Broker::Broker(rapidjson::Document *user_description_file)
            if(log_user_stats){
                PPK_ASSERT(user_description_file->HasMember("log_folder"),
                    "Invalid user_description file : field"
-                   "'log_folder' should be define with  'log_user_stats' ");
+                   "'log_folder' should be defined with 'log_user_stats' ");
                const Value &log_folder_param = (*user_description_file)["log_folder"];
                PPK_ASSERT(log_folder_param.IsString(),
                    "Invalid user_description file : field"