That's a great question and we're glad you reached out! While there's not a way to add a document link in the confirmation email for an event, you can send an email to all of your event registrants and include a link to your pdf document. From the Event Dashboard, click "Send email to registrants" and follow the prompts to create an email:
The email won't be sent to guests and you can email the non-responders separately. This is also a great way to later thank your registrants for attending your event!