pgsql: doc: Mention CASCADE/RESTRICT for DROP STATISTICS - Mailing list pgsql-committers

doc: Mention CASCADE/RESTRICT for DROP STATISTICS

This grammar has no effect as there are no dependencies on statistics,
but it is supported by the parser.  This is more consistent with the
other DROP commands.

Author: Vignesh C
Discussion: https://postgr.es/m/CALDaNm1LA=yNmzcSfy+0oe6CEAgsxXRf_-UutE3ZncFi8QkFNQ@mail.gmail.com
Backpatch-through: 10

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/e8321a3190bd491af7c67c1a73d8c043a216ec25

Modified Files
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doc/src/sgml/ref/drop_statistics.sgml | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)