This is an important lesson. Anytime you're onboarding a new user/employee, your documentation will benefit by getting that person's feedback. What's incorrect? Where there any steps that weren't clear? Or missing steps? Is there information that's outdated?

I've even gone as far as forcing the developers to answer questions by incorporating new information into the documentation. If you start having out-of-band communication (email, chats, in-person conversations) between the newbie and the team, there's a strong chance that extra information will never find its way back into the documentation.