Doc: add note about --buffer-usage-limit being v16 onwards
Other vacuumdb options seem to have notes about which version they're
available from, so let's follow this trend for the newly added
--buffer-usage-limit option.
Branch
------
master
Details
-------
https://git.postgresql.org/pg/commitdiff/e9f451accbde17d106ac6a92c8877992d4410629
Modified Files
--------------
doc/src/sgml/ref/vacuumdb.sgml | 6 ++++++
1 file changed, 6 insertions(+)
