Thank you so much!No. That's not what you do in a treatment. Do not use any script terminology in a treatment. That defeats the purpose of a treatment.
A treatment is written like a novel. If you want to explain essential background, you need to do that through the story. Give a reason for this exposition to happen, through visuals, character action, character conversations, what have you. But you need to describe everything in prose. Do not use voiceover.
Online there exists James Cameron's original treatment for Terminator. I suggest you reference that.