Updated README

Author: wripley

README.md

@@ -102,7 +102,7 @@ gcloud init
 ```
 
 ### Tools
-1. [Terraform >= 0.11.7](https://www.terraform.io/downloads.html)
+1. [Terraform >= 0.12](https://www.terraform.io/downloads.html)
 2. [Google Cloud SDK version >= 204.0.0](https://cloud.google.com/sdk/docs/downloads-versioned-archives)
 3. [kubectl matching the latest GKE version](https://kubernetes.io/docs/tasks/tools/install-kubectl/)