Tag 1040 is not just a note

[cabo]

@jyasskin notes that 4. The definition of tag 1040 starts with "Note" making it look
non-normative. I'd rather have that paragraph define the meaning of
the data item, like "The data item is interpreted the same as in tag
40 except that the second sub-array holds elements with the first
dimension contiguous (column-major order)."