Revise the scope note of E59 Primitive Value

The scope note of E59 Primitive Value (up until v7.4) states that its instances are not considered elements of the universe of discourse the CIDOC CRM aims to define and analyse. This formulation is potentially misleading, since certain E59 Primitive Value subclasses, namely E94 Space Primitive, E61 Time Primitive, and E95 Spacetime Primitive, are explicitly declared as subclasses of E41 Appellation and are therefore characterised ontologically as names within the CRM.

This issue is about redrafting the definition of E59.