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_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/973c41567f3ff1c3356a85388faa90443a9c010e

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