Add sd:SPARQL12Query and sd:SPARQL12Update, to sd:Language

[JervenBolleman]

https://w3c.github.io/sparql-service-description/spec/#sd-Language does not yet mention the 1.2 languages

[rubensworks]

The classes already exist (https://w3c.github.io/sparql-service-description/spec/#lang-sparql12query), but they should be mentioned in that section indeed. Good catch!