Make the distinction between ordered and unordered collections and relationships

[jdvorak001]

In some contexts, ordering of elements in a collection is important, e.g. keywords or authors of a document.
In other contexts, ordering is not important: e.g. contacts.

A convention should be introduced for the Markdown files.
This should then be somehow represented in the PlantUML diagrams and also in the generated ontology.

[jdvorak001]

In Markdown files:

• For attributes: use List<...> or Set<...>
• For relationships: At the end of the relationship paragraph, add the sentence "These are ordered." in case the order is important. If it is not important, nothing is added to the paragraph.

In PlantUML files:

• For attributes: use List<...> or Set<...>
• For relationships: Add <<ordered>> to the role in the direction where the ordering is important.

This translates into the ontology as follows:

• Single-valued properties are FunctionalProperties
• Unordered multi-valued properties are just properties.
• Ordered multi-valued properties have a domain of rdf:List. An additional SHACL shape could constrain the types of the elements.