Thread: pgsql: Use correct spelling of statistics kind

Use correct spelling of statistics kind

A couple error messages and comments used 'statistic kind', not the
correct 'statistics kind'. Fix and backpatch all the way back to 10,
where extended statistics were introduced.

Backpatch-through: 10

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/16568c0a8aee85052cfd3e465d21d1e1d1b442e1

Modified Files
--------------
doc/src/sgml/catalogs.sgml              | 2 +-
src/backend/statistics/dependencies.c   | 2 +-
src/backend/statistics/extended_stats.c | 2 +-
src/backend/statistics/mvdistinct.c     | 2 +-
src/include/nodes/relation.h            | 2 +-
5 files changed, 5 insertions(+), 5 deletions(-)