Documentation: process: Revert "Document suitability of Proton Mail for kernel develo...

Documentation: process: Revert "Document suitability of Proton Mail for kernel development"

Revert commit 1d2ed9234c85 ("Documentation: process: Document
suitability of Proton Mail for kernel development") as Proton disabled
WKD for kernel.org addresses as a result of some interaction with
Konstantin on social.kernel.org

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Kanak Shilledar <kanakshilledar111@protonmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240516-groin-slingshot-c3c3734d2f10@spud