Use written language codes for Norwegian

[petterreinholdtsen]

There is no 'no/Norwegian' written language, the existing ones use either 'nb/Norwegian Bokmål' or 'nn/Norwegian Nynorsk'. As the majority is written in Norwegian Bokmål, those using 'no' as the language code is most likely meaning the 'nb' variant. Please avoid using the unspecific 'no' language code.