Document the NDR constraints on cardinality in revisions and subsets

In the NDR document, the constraints on cardinality are not documented for the situations where changes in cardinality are considered: revisions and subsets.

When a vocabulary is revised, a BIE's cardinality can be changed to be a superset of the old cardinality. The new minimum can be lowered and/or the new maximum can be raised from the old values.

When a vocabulary is subset, a BIE's cardinality can be constrained to be a subset of the old cardinality. The new minimum can be raised and/or the new maximum can be lowered from the old values.