pgsql: doc: FreeBSD uses camcontrol identify, not atacontrol, for cache

doc: FreeBSD uses camcontrol identify, not atacontrol, for cache

This is for IDE drive cache control, same as SCSI (already documented
properly).

Reported-by: John Ekins

Discussion: /messages/by-id/20170808224017.8424.69170@wrigleys.postgresql.org

Author: John Ekins

Backpatch-through: 12

Branch
------
REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4e64be6520dbc67febbf8ecd8fe28bad06c0255c

Modified Files
--------------
doc/src/sgml/wal.sgml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)