pgsql: Fix nbtree skip array transformation comments.

Fix nbtree skip array transformation comments.

Fix comments that incorrectly described transformations performed by the
"Avoid extra index searches through preprocessing" mechanism introduced
by commit b3f1a13f.

Author: Yugo Nagata <nagata@sraoss.co.jp>
Reviewed-By: Chao Li <li.evan.chao@gmail.com>
Reviewed-By: Peter Geoghegan <pg@bowt.ie>
Discussion: https://postgr.es/m/20251230190145.c3c88c5eb0f88b136adda92f@sraoss.co.jp
Backpatch-through: 18

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/8aed8e168fd2d2075a8f2622a980ed8991a69895

Modified Files
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src/backend/access/nbtree/nbtpreprocesskeys.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)