Updated dead-letter-exchange.txt

AlexanderSemenets authored
revision 2cbbf6e8108846efbbbd956929da4099ecec595b
# Dead Letter Exchange

Write here..It is possible to form a cycle of message dead-lettering. For instance, this can happen when a queue dead-letters messages to the default exchange without specifiying a dead-letter routing key. Messages in such cycles (i.e. messages that reach the same queue twice) will be dropped if there was no rejections in the entire cycle.