If your switch is a normally open momentary switch you could wire one side to Vcc and the other to pin 15. The internal pull down will keep pin 15 LOW during reset. After reset, pressing the button will pull pin 15 HIGH.
If your switch is a normally open momentary switch you could wire one side to Vcc and the other to pin 15. The internal pull down will keep pin 15 LOW during reset. After reset, pressing the button will pull pin 15 HIGH.