pgsql: Last-minute updates for release notes.

Last-minute updates for release notes.

Security: CVE-2026-2003, CVE-2026-2004, CVE-2026-2005, CVE-2026-2006, CVE-2026-2007

Branch
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REL_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/30d2603f5c340133ca03e098fcaa9c242843d5e1

Modified Files
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doc/src/sgml/release-18.sgml | 208 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 207 insertions(+), 1 deletion(-)