Language Spec Comment: Change Cardinality to Multiplicity

The terms Cardinality and Multiplicity are often used interchangeably, see for example https://www.uml-diagrams.org/multiplicity.html - "Multiplicity is a definition of cardinality - i.e. number of elements"

However as James Rumbaugh points out, this is technically incorrect.  Cardinality refers to a single number, while multiplicity is "A specification of the range of allowable cardinality values".  (https://martinfowler.com/bliki/MultiplicityNotCardinality.html).

For consistency with UML, wherever OpenC2 refers to a range of cardinalities, it should use the word multiplicity instead.  The type definition tables use the symbol "#" for this range, so this issue requires no change to table headers or contents.