1181 Documents specifications need classific

Typical_document_specification is documented to be a "reusable" design but the standard instances appear to be a mixture of class and class-of-class (e.g., "map" and "bathymetry map") of document specification.

Add entities and relationships

Add entities Document_specification_class, Document_specification_classification and Document_spec_class_classification. This includes relationships between the new entities. Add relationship to allow Document_specification to be classified.

Added objects:
document_specification_classification (Entity)
document_specification.document_specification_classification (Attribute)
document_specification_class (Entity)
document_spec_class_classification (Entity)

Modify diagram

Modify diagram DMC to add the new entities.

Modified objects:
DMC:_Document_Classification (Diagram)