use skos:scopeNote instead of vann:usageNote

[VladimirAlexiev]

vann:usageNote provides useful additional notes about OML terms.

However, the definition of http://purl.org/vocab/vann/usageNote says:

• A reference to a resource that provides information on how this resource is to be used.

• It is a sub-property of See also.

So it's a URL not a string, and you cannot use it like this.

Use skos:scopeNote instead, which is a literal, and can be used with any resource (not only skos:Concept)