[Docs] use IAO:has ontology root term for better visibility of root terms in TS

[StroemPhi]

has ontology root term can be used for better display the terms in an ontology that are considered "roots", that is central upper most terms. Often very abstract parent classes of these root terms can then be hidden in terminology services, which helps to keep the focus and get a better overview of the actual ontology. We should do this in VIBSO whenever possible for these reasons.