Some readability enhancements

[petrisch]

While reading the docs I might as well contribute to where I was stumbling over the text.
I'm not a native english speaker, so I might be wrong here and there.

Also the whitespace corrections might be too opiniated. Feel free to ignore them.

Great project btw, I'm planning to use it in a little project.

[petrisch]

Oh and the "```nushell" might only work for github.
Not sure if it works for the website...

[petrisch]

It is nu of course not nushell.

[ddanier]

@petrisch Wow, amazing!

The nu syntax highlighting sadly does not work. This is due to the fact, that the docs are built using just-the-docs which is using rouge (https://rouge.jneen.net/) for syntax highlighting....and this just doesn't support nu (yet?).

I will revert this, then merge the changes. Thank you so much!