Mark repo as deprecated/unmaintained

[wincent]

For reasons noted in the new README.

[wincent]

@kassens: as per our chat the other day, here's a proposed change.

Rather than having this thing sitting around poorly maintained, I think it's better to shutter it and instead focus on making the documentation great (and potentially building a create-relay-app like you mentioned).

[kassens]

Thanks for sending this out, makes a lot of sense to me until someone brings up the energy to bring this up to date again (but that energy would most likely be better channeled into create-relay-app or documentation