pgsql: doc: Update pg_size_pretty documentation about petabytes support

doc: Update pg_size_pretty documentation about petabytes support

Missing documentation update for ca2e4472ba.

Discussion: /messages/by-id/CAApHDvrCwMgSD_93LZr4CLMas8Hc61fXAQ-Cd4=+yoRfHnYbJA@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/af4d5715fc73c2ae2a22226e6f46958201464955

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