Add information about media that cannot be imaged using the BCE

[a-berish]

Imaging documentation should include cutoff for hardware/media that is not imageable, and provide links for alternate tools to turn to (e.g., older hardware, RAID disks). Updated (6/28/2023) with another related Google Group thread about older hardware compatibility.

https://groups.google.com/g/bitcurator-users/c/WLpazhahCxc
https://groups.google.com/g/bitcurator-users/c/FP9EjtBfKdI
https://groups.google.com/g/bitcurator-users/c/ShltU1MSTCg