Clarify that Kiosk feature is not yet available

[Popolechien]

I am currently testing the latest test-image (2026-03) and I see that the Kiosk feature can not be turned on. Is this on purpose because while it is planned, it is not available yet?

If this is the case I would recommend adding a SOON label next to it.

[rgaudin]

Indeed, feature does not exists yet.