pgsql: doc: rename "decades" to be more generic

doc: rename "decades" to be more generic

Reported-by: Michael Paquier

Discussion: /messages/by-id/ZJTzwD2rTbHWWQ9g@paquier.xyz

Backpatch-through: 11

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4f8f0f8c397ee855caed36c7994b2450b11278b1

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