docs: Use justified text alignment in user guide

[stinodego]

I am not 100% sure about this, but I think it reads a bit nicer. Thoughts @r-brink @c-peters ?

Before

After

[ritchie46]

Now I read double spaces?😅

[c-peters]

Although it looks nice visually, I find the reading experience to get a lot worse and would not be in favor

[r-brink]

In general I also prefer the non justified text. In some parts it looks and reads better, but in many places the spacing becomes very wide

[stinodego]

All right, let's close it then!