pgsql: relnotes: improve collation check and ICU items

relnotes: improve collation check and ICU items

Reported-by: Matthias van de Meent

Discussion: /messages/by-id/CAEze2WhrNAT2g8upDUhfqt1nWfV_JdUgXAQu7oT4rY2L68O-HQ@mail.gmail.com

Backpatch-through: 15 only

Branch
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REL_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4ddcb20592270ac3aa1082531d8057ca3d229951

Modified Files
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doc/src/sgml/release-15.sgml | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)