mdadm documentation is referencing deprecated MachineConfig

[dbackeus]

The documentation for the mdadm extensions mentions using machine.disks to partition and mount a RAID device: https://github.com/siderolabs/extensions/tree/main/storage/mdadm#let-talos-format-software-raid

However this property has been deprecated in favour of UserVolumeConfig.

Would be nice to see the documentation updated to work on recent Talos versions.

[frezbo]

PR's are welcome 👍