examples: Add example for atomic write verify

Add an example for verifying atomic writes.

Until now, atomic writes are only supported on Linux for block devices, so
only give instructions on for that.

Currently support is being worked on for XFS and EXT4, and instructions can
be updated in due course.

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240916165347.2226763-10-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
1 file changed