Fix #523
Fix #523

@jnivre wrote it is "very clear that an `appos` should itself be a noun phrase, not a clause." and the example is a mistake.
Fixes #523
UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs,UniversalDependencies/docs