pgsql: Document that && geometric operator is true even if only a point

Log Message:
-----------
Document that && geometric operator is true even if only a point
overlaps.

David Fetter

Modified Files:
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pgsql/doc/src/sgml:
func.sgml (r1.513 -> r1.514)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.513&r2=1.514)