doc: Use better placeholder in COPY synopsis
Branch------master
Details-------https://git.postgresql.org/pg/commitdiff/1c4429e703b2caf7fc865c2fc0a94f3557e5b356
Modified Files--------------doc/src/sgml/ref/copy.sgml | 2 +-1 file changed, 1 insertion(+), 1 deletion(-)
