doc: fix sysfs directory in README file
doc: fix sysfs directory in README file

The README documentation were pointing to the wrong
directory for byte_queue_limits stats, fix that.

Signed-off-by: Jesper Dangaard Brouer <980bdea81946be3dffddbcbbdb1b5761713ff28c@redhat.com>

dtaht/bqlmon,ffainelli/bqlmon