Terraform 0.12 (#20)

* Terraform 0.12

first-steps/instance.tf

@@ -8,3 +8,4 @@ resource "aws_instance" "example" {
   ami           = "ami-0d729a60"
   instance_type = "t2.micro"
 }
+

first-steps/versions.tf

@@ -0,0 +1,4 @@
+
+terraform {
+  required_version = ">= 0.12"
+}