pgsql: Document "B" and "us" as accepted units in postgres.conf.sample

Document "B" and "us" as accepted units in postgres.conf.sample

In postgresql.conf, memory and file size GUCs can be specified with "B"
(bytes) as of b06d8e58b. Likewise, time GUCs can be specified with "us"
(microseconds) as of caf626b2c. Update postgres.conf.sample to reflect
that fact.

Pavel Luzanov

Backpatch to v12, which is the earliest version that allows both of
these units. A separate commit will document the "B" case for v11.

Discussion: https://www.postgresql.org/message-id/flat/f10d16fc-8fa0-1b3c-7371-cb3a35a13b7a%40postgrespro.ru

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4b39d5c69a67caebe648ce4c32083f162bd239e1

Modified Files
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src/backend/utils/misc/postgresql.conf.sample | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)