idk, I appreciate the way they appropriately set expectations up-front
Basically "Hey, this is hard. Really hard. If you don't actually care, you can probably just use XYZ. If that doesn't work, try just reading sections 1 and 4. Otherwise... settle in, it's gonna be a slog."
They're called letters OP, and you read them by stringing them together into things we call words. I know its hard without a YouTube video to tell you.
OK. You read the text in the image, and obviously find it easy to understand.
So what would you use par for in practice, and what would I type into my terminal to use it?
Why would you use it in the terminal? You pair this with a text editor and use it to spruce up the formatting after you're done. In Vim I select it with the visual select and type !par and it formats for me. You also have to know when to use what tools and why you use them. Just telling people to use this to format a text doc doesnt make much sense because theres no end goal in mind.
But to satisfy you:
par <example.txt>
On the other hand, the doc itself says the docs are not user friendly and apologizes for it. Which not all do because a lot are easy. Like Kitty's docs are amazing.