Consider replacing the linear array redundancy level in the docs

[hrismarin]

Currently, the Butane and Ignition docs state:

• level (string): the redundancy level of the array (e.g. linear, raid1, raid5, etc.).

Some md personalities, including linear, have been deprecated in the Linux kernel, see:
Ignition fails at raid creation
torvalds/linux@608f52e
torvalds/linux@849d18e

Should we consider removing or replacing the explicit mention of the linear array redundancy level from the Butane and Ignition docs?

[travier]

That's a good point. If the configs are not longer accepted by the kernel and haven't been for a while then butane should probably not accept them as well.

Removing them from the docs is a good first step. Adding some logic in butane or ignition to fail validation in a second step would be good as well. We can probably start in Butane as that could be considered a breaking change in Ignition so not sure if we can do that in a regular spec bump.