Clarify language in 4.1.1 Non normative example

I think the example is correct though it depends on where you place the emphasis as to how you interpret it. The point is that the message must get to the server in spite of failures, the following would this make it clearer. 4.1.1 Non normative example For example, a user wishing to gather electricity meter readings may decide that they need to use QoS 1 messages because they need to protect the readings against loss over the network, however they may have determined that the power supply is sufficiently reliable that the data in the Client and Server can be stored in volatile memory without too much risk of its loss. Conversely a parking meter payment application provider might decide that the payment message should never be lost due to either the network or the client or systems failing. Consequently they require that all data are force written to non-volatile memory before being transmitted across the network.