Update links to distribution packages

[UnlimitedCookies]

Fedoras new link: https://packages.fedoraproject.org/pkgs/ghc-hakyll/ghc-hakyll/
Archlinux's package could also be added: https://archlinux.org/packages/extra/x86_64/haskell-hakyll/

And perhaps documentation could be added how to use Hakyll when it was installed as a system library. One way is to add the runhaskell shebang to the head of the site.hs file for example.