Add rdfs:seeAlso for types

[frmichel]

For types (classes), add an rdfs:seeAlso to https://github.com/tdwg/PlinianCore/wiki/[TypeName] if this is a "native" type, i.e. if it exists in the XSD.
But do not add such property for types that are made up for anonymous complex types, e.g. ParentTaxonType.