Deploying section out of date

And has said it will be updated "soon" for probably a year or more? Even just removing most of that page and linking to `Fastboot App Server` repo would be an improvement.

However there's also an opportunity here to iron out some confusion about the difference between [ember-cli-fastboot](https://github.com/ember-fastboot/ember-cli-fastboot) & [fastboot-app-server](https://github.com/ember-fastboot/fastboot-app-server), since I think people are frequently confused about this.

There's also an opportunity to create a generic Fasboot App Server that can be deployed to Heroku and configured with environment variables. IMO this is sorely needed and pretty low-hanging fruit. My company had one briefly but we have added some proprietary customizations & are no longer comfortable keeping it open source. However we could probably keep an older, generic version open source if that's helpful.