lib/kstrtox: fix kstrtobool() docstring to mention enabled/disabled

lib/kstrtox: fix kstrtobool() docstring to mention enabled/disabled

Commit ae5b3500856f ("kstrtox: add support for enabled and disabled in
kstrtobool()") added support for 'e'/'E' (enabled) and 'd'/'D' (disabled)
inputs, but did not update the docstring accordingly.

Update the docstring to include 'Ee' (for true) and 'Dd' (for false) in
the list of accepted first characters.

Link: https://lkml.kernel.org/r/20251227092229.57330-1-chaitanyamishra.ai@gmail.com
Fixes: ae5b3500856f ("kstrtox: add support for enabled and disabled in kstrtobool()")
Signed-off-by: Chaitanya Mishra <chaitanyamishra.ai@gmail.com>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>