doc:it_IT: fix a typo in the config name in RCU torture

This issue was detected with the scripts/checkkconfigsymbols.py tool.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240207150322.20238-1-lukas.bulwahn@gmail.com