My guess would be they want to see one of your performance reviews from your current job. I've never had a prospective employer ask for something like that, but I've never worked for a state prison system either. You could just send them the license info and application and ask what they want for the report. The thing with reviews is that they generally don't say all that much that is useful unless they are bad and then they have lots of detail. Otherwise they are so generic and overrated since even average performers never get negative reviews. And you can always cherry pick the one you send, so I see even less relavancy there.
You may shoot yourself in the foot by not including it or you may not. Probably depends on how many other folks want to work in the prison system. Good luck with it, cant say it would be my first choice.