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

Proton Mail automatically picks up PGP keys for those with kernel.org
accounts (and other domains!) which provide WKD for their users & uses
them to encrypt emails, including patches.

Document the behaviour & Proton Mail's unsuitability for kernel
development.

Reviewed-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221231152320.1340874-1-conor@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation: process: Update email client instructions for Thunderbird

The instructions don't match with the current Thunderbird interface.
Clarification on using external extensions.
New information on how to avoid writing HTML emails.
Tell user to restart Thunderbird after modifications.

Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Sotir Danailov <sndanailov@gmail.com>
Link: https://lore.kernel.org/r/20220715211307.9358-1-sndanailov@gmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/process: expand plain-text advice

This adds a link to https://useplaintext.email to email-clients.rst,
which is a more exhaustive resource on configuring various mail clients
for plain text use. submitting-patches.rst is also updated to direct
readers to email-clients.rst to equip new contributors with the
requisite knowledge to become a good participant on the mailing lists.

Signed-off-by: Drew DeVault <sir@cmpwn.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20200903160545.83185-3-sir@cmpwn.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Replace dead urls with active urls for Mutt

This patch replace stale/dead urls with active urls for Mutt.

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: email-clients miscellaneous fixes

Fixed some style inconsistencies and remove old statement referring to
kmail missing feature (saving email from the view window is possible).

Signed-off-by: Federico Vaga <federico.vaga@vaga.pv.it>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

doc: Document suitability of IBM Verse for kernel development

IBM Verse is a web UI around Lotus Domino mail servers (much like
the Lotus Notes client talks to Domino servers).

For various reasons, it is not at all suitable for kernel development,
all of which have been raised (repeatedly) internally.

Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Acked-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

docs-rst: add documents to development-process

Add several documents to the development-process ReST book.

As we don't want renames, use symlinks instead, keeping those
documents on their original place.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>