pgsql: doc PG 18 relnotes: move ANALYZE item,split ANALYZE/EXPLAIN item

doc PG 18 relnotes: move ANALYZE item,split ANALYZE/EXPLAIN item

Reported-by: Yugo Nagata

Author: Yugo Nagata

Discussion: /messages/by-id/20250528232503.7db770f651c2c821c0e3c1df@sraoss.co.jp

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/bf6034d00dd4c7e82fe281df5a22c8e49ad76dde

Modified Files
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doc/src/sgml/release-18.sgml | 47 ++++++++++++++++++++++++++------------------
1 file changed, 28 insertions(+), 19 deletions(-)