pgsql: Fix grammar in short description of effective_wal_level.

Fix grammar in short description of effective_wal_level.

Align with the convention of using third-person singular (e.g.,
"Shows" instead of "Show") for GUC parameter descriptions.

Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20260210.143752.1113524465620875233.horikyota.ntt@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/a596d27d807974778513158cb0eafc76bae33d97

Modified Files
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src/backend/utils/misc/guc_parameters.dat | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)