Generally speaking, I'll just point someone to documentation if:

1. Their question is vague
2. It's obvious they didn't do any reasonable amount of research before asking
3. or when there's not much I could add to the documentation

If it's clear that the querant has tried their even best before asking for help, they're more likely to get an annotated solution -- because, at that point, it's probably the most efficient way of instructing them.