make ArticleProcessingCharge nodes resolvable #118
Description
curl -Haccept:text/turtle https://semopenalex.org/work/W1965376857
... soa:hasAPCPaid <https://semopenalex.org/articleProcessingChargePaid/W1965376857>;
But that URL doesn't resolve. Applies to eg
- https://semopenalex.org/articleProcessingChargePaid/W1965376857
- https://semopenalex.org/articleProcessingChargeList/W2135597156
This issue also applies to articleProcessingCharge/source/Snnnn (see #117)