osd/scrub: clarify that osd_scrub_auto_repair_num_errors counts objects

osd/scrub: clarify that osd_scrub_auto_repair_num_errors counts objects

'osd_scrub_auto_repair_num_errors' limits the number of damaged objects
that we will try to auto-repair during a scrub. Its documentation
referred to "number of errors", which did not fit the implementation.

Fixes: https://tracker.ceph.com/issues/71754
Fixes: Red Hat BZ2316244
Signed-off-by: Ronen Friedman <rfriedma@redhat.com>
(cherry picked from commit 680b58ffd0bf5b213ec525f8d783297fb0b14343)
Signed-off-by: Ronen Friedman <rfriedma@redhat.com>