pgsql: doc PG 19 relnotes: add two optimizer hooks

doc PG 19 relnotes: add two optimizer hooks

Reported-by: Jian He

Discussion: /messages/by-id/CACJufxE8Ew_DCXtd1VZSC=pNPHqZRa4RJkbCr7z6ZPJJ3o3hGQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/cac0f24eb57f628c59e026e5b924f9d9ee4d7353

Modified Files
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doc/src/sgml/release-19.sgml | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)