Debra,
I have never noticed a natural place for checkout instructions, so I email them, which seems to be the norm based on articles that I have read. These guest received my email, which AirBnB can see was sent, that contained the instructions.
Based on your input, I went in and added them in my house rules and in the listing section "other things to note". Thanks for that suggestion. I honestly do not think it would have made a difference with these renters. I clearly had quiet hours and the non-smoking rule listed in my house rules and they violated both of those rules. My neighbor even had to call the police on their first night.
These renters are the exception to the norm. 99.9% of our renters have been wonderful and I have enjoyed sharing ideas with them.
Thank you for your helpful response.