* Discontinue using Matchbox's Container Linux Config features
* Flatcar Linux OS now supports Ignition v2.13+ which means it
can accept Ignition v3.x spec's, like Fedora CoreOS. Matchbox
supports this by serving Ignition documents directly
* Users of the poseidon/matchbox Terraform provider can pass
a `matchbox_profile` `raw_ignition` contents with the desired
Ignition v3.3 spec
* Users of the poseidon/ct Terraform provider can write Butane
Config YAML, perform templating, and render an Ignition document
using either the fcos or the flatcar variant
* Refactor examples to boot provision minimal hosts
with Fedora CoreOS or Flatcar Linux
* Remove the etcd3 cluster example or other specific
kinds of hosts
* Update script get-fedora-coreos
* Remove script get-coreos
