Step4 needs to have boot script root.js disabled

[crandmck]

Per strongloop/loopback#2012, there is a small problem with step4. When I check out that release, it is not reflecting the change made in Change or modify the default root route handler -- that is, server/boot/root.js should be renamed to server/boot/root.js.disabled or it could just be deleted (it doesn't matter, since it will work either way, but it might be more obvious if the file is there but just renamed with a non-.js extension).

[superkhau]

Closing as all steps have been removed as of 3.x upgrades. We'll need to upgrade the loopback.io docs instead.