* Emphasize that Container Linux Configs have been dropped and
that Butane is the way forward to use modern Ignition v2
* Include some links to Flatcar Linux docs
* Update Makefile and docs for v0.10.0 release process
* Deprecate rendering Container Linux Configs
* Use tools like [poseidon/ct](https://github.com/poseidon/terraform-provider-ct) or
[butane](https://coreos.github.io/butane/getting-started/) to validate and convert a
Butane Config (`focs` or `flatcar`) to Ignition (for Matchbox to serve)
* Please migrate to serving CoreOS Ignition directly, the Container
Linux related HTTP and gRPC endpoints will be removed in future
