Add module version requirements to internal workers modules

aws/container-linux/kubernetes/workers/require.tf

@@ -0,0 +1,9 @@
+# Terraform version and plugin versions
+
+terraform {
+  required_version = ">= 0.10.4"
+}
+
+provider "aws" {
+  version = "~> 1.7"
+}

docs/advanced/worker-pools.md

@@ -79,6 +79,10 @@ Create a cluster following the Google Cloud [tutorial](../google-cloud.md#cluste
 module "yavin-worker-pool" {
   source = "git::https://github.com/poseidon/typhoon//google-cloud/container-linux/kubernetes/workers?ref=v1.9.4"
 
+  providers = {
+    google = "google.default"
+  }
+
   # Google Cloud
   region  = "us-central1"
   network = "${module.google-cloud-yavin.network_name}"

google-cloud/container-linux/kubernetes/workers/require.tf

@@ -0,0 +1,9 @@
+# Terraform version and plugin versions
+
+terraform {
+  required_version = ">= 0.10.4"
+}
+
+provider "google" {
+  version = "~> 1.2"
+}