Improved definition of the metadata field issue

[pedropaulofb]

The Software Process Ontology (dataset spo2017) was created in 1998 using a language different from OntoUML for its formalization. Later, this ontology was migrated to OntoUML (created only in 2005).

Currently, the issue date of this ontology registered in its metadata file is 1998. However, we must analyze and reconsider this situation, as it is going to generate inconsistent results when evaluating the catalog's data. We can:

• define the issue field as the first year the ontology was created using OntoUML or UFO, or
• create another metadata field

Personally, I think that the best option would be the first. The information of the original creation of the ontology could be inserted into the editorialNote field.

[pedropaulofb]

The Issue https://github.com/unibz-core/ontouml-models/issues/235 can be closed after this one.

[pedropaulofb]

Done.