pgsql: doc: Small example improvement

doc: Small example improvement

Add a comment character before a line annotation, so that the query
can be used as presented.

Reported-by: Yaroslav Saburov <y.saburov@gmail.com>
Author: Euler Taveira <euler@eulerto.com>
Reviewed-by: Robert Treat <rob@xzilla.net>
Discussion: https://www.postgresql.org/message-id/flat/174393459040.678.17810152410419444783%40wrigleys.postgresql.org

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/913c60b067aa1a618420fd0372c4df3cf5501863

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