doc: correcting the debug path for cachefiles

The original debug path is under "/sys/modules", that's
wrong. The real path in kernel is "/sys/module". So we
can correct it.

Signed-off-by: Hongbo Li <lihongbo22@huawei.com>
Link: https://lore.kernel.org/r/20241022013812.2880883-1-lihongbo22@huawei.com


Signed-off-by: Christian Brauner <brauner@kernel.org>