link to non-existent tutorials/tutorial3.html

[p-alik]

The link behind "Managed Processes tutorial" in last paragraph of Managed Processes points to non-existing site http://haskell-distributed.github.io/tutorials/tutorial3.html

I guess it should be replaced by https://haskell-distributed.github.io/tutorials/4ch.html

[p-alik]

It's done in PR #40