Thread: pgsql: Update comments about index parallel builds

Update comments about index parallel builds

Commit b43757171470 allowed parallel builds for BRIN, but left behind
two comments claiming only btree indexes support parallel builds.

Reported by Egor Rogov, along with similar issues in SGML docs.
Backpatch to 17, where parallel builds for BRIN were introduced.

Reported-by: Egor Rogov
Backpatch-through: 17
Discussion: https://postgr.es/m/114e2d5d-125e-07d8-94aa-5ad175fb7443@postgrespro.ru

Branch
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REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/42eae257cfcaa1d20e4f555d14934388ac434c61

Modified Files
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src/backend/catalog/index.c          | 2 +-
src/backend/optimizer/plan/planner.c | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)