docs: debugging: add more info about devcoredump

docs: debugging: add more info about devcoredump

Correct a few small things in the devcoredump synopsis and then add
the devcoredump APIs to it.

Fixes: a037699da0a1 ("docs: Add debugging section to process")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Sebastian Fricke <sebastian.fricke@collabora.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: workflows@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241130081107.552503-1-rdunlap@infradead.org