samples/kobject: fix path comment

The introductory comment still says the example creates
/sys/kernel/kobject-example, but the code actually creates
/sys/kernel/kobject_example.

Update both comments to reflect the actual sysfs paths. Also,
fix "tree"->"three" typo in kset-example.c.

Signed-off-by: Meng Shao Liu <sau525@gmail.com>
Link: https://lore.kernel.org/r/5be61d284a1850f573658f1c105f0b6062e41332.1752646650.git.sau525@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>