The upstream of this repo (MvvmCross/MvvmCross-Tutorials) seems to be deleted. Now the upstream is changed to Cheesebaron/MvvmCross-Tutorials which seems to be very outdated. I'll try to update this repo by myself.
In my opinion, it's a mistake to delete MvvmCross/MvvmCross-Tutorials from GitHub, because this repo have many good simple but helpful projects, just like it says, tutorials. I learned MvvmCross and actually native Xamarin.Android and Xamarin.iOS from this kind of repos.
PR is welcome if anyone is interested to keep the tutorials up to date with latest version of MvvmCross.