Update docs/Backup & restore.md

Remove normative language

Co-authored-by: jonathan-r-thorpe <[email protected]>

docs/Backup & restore.md

@@ -93,7 +93,7 @@ A `device`, for the purposes of this section, is a physical or logical entity th
 
 `Backup data set` is the set of data retrieved from a device using the backup procedures described.
 
-`Device revision` represents any combination of software versions (this includes firmware) and hardware revision that dictates the functionality of the device. As a vendor evolves a product through its lifecycle the hardware, software and/or firmware that make up a device is likely to change. From time to time a vendor my issue new software or firmware that a customer can install that changes how a device behaves. A device may also have hardware such a peripherals or plug-in cards added or removed that change its behaviour. Each of these changes can affect how easily a `backup data set` can be restored to a device. The `device revision` is used to represent the ensemble of the versions of all the various components that affect a device’s functionality. It is up to a vendor to decide what changes to a device represent a change of `device revision`. A software upgrade will likely result in a device being considered to have a different `device revision` but a vendor may decide that a change in, for example, PCB colour does not represent a different `device revision`.
+`Device revision` represents any combination of software versions (this includes firmware) and hardware revision that dictates the functionality of the device. As a vendor evolves a product through its lifecycle the hardware, software and/or firmware that make up a device is likely to change. From time to time customers install new software or firmware issued by the vendor that changes how a device behaves. Changes to a device's hardware, such a peripherals or plug-in cards added or removed, could also change its behaviour. Each of these changes can affect how easily a `backup data set` is restored to a device. The `device revision` is used to represent the ensemble of the versions of all the various components that affect a device’s functionality. It is up to a vendor to decide what changes to a device represent a change of `device revision`. A software upgrade will likely result in a device being considered to have a different `device revision` but a vendor could decide that a change in, for example, PCB colour does not represent a different `device revision`.
 
 `Backup validation fingerprint` is an optional string in a `backup data set` that can be used to capture the various versions of the hardware, software and/or firmware that made up a device at the time the backup was performed. The `backup validation fingerprint` can be used by a device to help decide whether the `backup data set` being restored to it is compatible. The format of the string is defined by the vendor and is opaque to other systems. This may contain information like: