Update CHANGES for v0.4.0 release

Author: dghubble

CHANGES.md

@@ -4,6 +4,8 @@ Notable changes between releases.
 
 ## Latest
 
+## v0.4.0
+
 * Support Fedora CoreOS Config `content` ([#52](https://github.com/poseidon/terraform-provider-ct/pull/52))
   * Render Container Linux Config `content` in Ignition v2.2 format
   * Render Fedora CoreOS `content` in Ignition v3.x format (determined by their own [version](https://github.com/coreos/fcct/blob/master/docs/configuration-v1_0.md))

README.md

@@ -19,6 +19,7 @@ Render the config with Terraform for machine consumption.
 data "ct_config" "worker" {
   content      = file("worker.yaml")
   pretty_print = false
+  strict       = true
 }
 
 resource "aws_instance" "worker" {