Tutorial: use cabal run instead of cabal exec

[ulysses4ever]

This is a bit subjective but I consider exec a more esoteric command and wouldn’t use it in a beginners tutorial unless absolutely needed. It’s also confusing when you switch between the two commands without any explanation.

note: the screenshot at the top also uses exec. I’d suggest to change that too.

[ulysses4ever]

One workaround for the annoying message is to call cabal run -v0. Of course, at this point, it's not clear what is the better alternative...