doc: Document range_intersect_agg(anymultirange)
It already existed but was not mentioned in the documentation. (Only
the anyrange variant was listed.)
Author: Paul Jungwirth <pj@illuminatedcomputing.com>
Reviewed-by: Chapman Flack <chap@anastigmatix.net>
Discussion: https://www.postgresql.org/message-id/flat/
007ef255-35ef-fd26-679c-
f97e7a7f30c2@illuminatedcomputing.com