Pekka Paalanen authored Mar 11, 2022 and Marius Vlad committed Mar 14, 2022

Tablet shell was removed in 873b515a in
2013. Time to remove the hopefully last reference to it.

We also gained kiosk shell in the mean time, so mention that instead.
Yes, it's a bit of a lie, because we also have ivi-shell and
fullscreen-shell, but I heard they might be on their way out, so I
didn't add them here.

Would be nice to add kiosk-shell in the SHELLS section too, but in this
patch I am only concerned about dropping the tablet shell reference.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>