Обсуждение: pgsql: Doc: fix incorrect example of collecting arguments with fmgrmac

Doc: fix incorrect example of collecting arguments with fmgr macros.

Thinko in commit f66912b0a.  Back-patch to v10, as that was.

Discussion: https://postgr.es/m/154522283371.15419.15167411691473730460@wrigleys.postgresql.org

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/c9a1c55a8b342cd00ffa810dfa63620ce6d497da

Modified Files
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doc/src/sgml/spi.sgml | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)