Add json-ld context for conceptschemes
user
```jsonld
{
  "@context": {
    "@vocab": "http://www.w3.org/2004/02/skos/core#",
    "@base": "http://libris.kb.se/",
    "rdfs": "http://www.w3.org/2000/01/rdf-schema#",
    "dc": "http://purl.org/dc/terms/",
    "foaf": "http://xmlns.com/foaf/0.1/",
    "title_en": {"@id": "dc:title", "@language": "en"},
    "title": "dc:title",
    "language": {"@id": "dc:language", "@language": null},
    "notation": {"@language": null},
    "comment": "rdfs:comment",
    "seeAlso": {"@id": "rdfs:seeAlso", "@type": "@id"},
    "homepage": {"@id": "foaf:homepage", "@type": "@id"},
    "@language": "sv"
  }
}
```
assistant