Django project templates for Django 2.x

[bittner]

trafficstars

The documentation mentions a Django project template for Django 1.8. There don't seem to be project templates for Django versions > 1.8. Can we add those?

[bittner]

Related: #184.

We probably won't need to cover Django 1.9 and 1.10 anymore. I'll update the issue title.

[PeterJCLaw]

While Django is now at 4.x, this appears to still be an issue. Updated docs link: https://django-configurations.readthedocs.io/en/stable/cookbook.html#project-templates