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

Revert commit 1d2ed923 ("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

Documentation/process/email-clients.rst

@@ -350,23 +350,3 @@ although tab2space problem can be solved with external editor.
 
 Another problem is that Gmail will base64-encode any message that has a
 non-ASCII character. That includes things like European names.
-
-Proton Mail
-***********
-
-Proton Mail has a "feature" where it looks up keys using Web Key Directory
-(WKD) and encrypts mail to any recipients for which it finds a key.
-Kernel.org publishes the WKD for all developers who have kernel.org accounts.
-As a result, emails sent using Proton Mail to kernel.org addresses will be
-encrypted.
-Unfortunately, Proton Mail does not provide a mechanism to disable the
-automatic encryption, viewing it as a privacy feature.
-The automatic encryption feature is also enabled for mail sent via the Proton
-Mail Bridge, so this affects all outgoing messages, including patches sent with
-``git send-email``.
-Encrypted mail adds unnecessary friction, as other developers may not have mail
-clients, or tooling, configured for use with encrypted mail and some mail
-clients may encrypt responses to encrypted mail for all recipients, including
-the mailing lists.
-Unless a way to disable this "feature" is introduced, Proton Mail is unsuited
-to kernel development.