Update recommended Terraform versions and providers

* Sync the documented Terraform versions and provider
plugin versions to those that are actively used/tested
by the author

docs/cl/aws.md

@@ -1,6 +1,6 @@
 # AWS
 
-In this tutorial, we'll create a Kubernetes v1.17.3 cluster on AWS with Container Linux.
+In this tutorial, we'll create a Kubernetes v1.17.3 cluster on AWS with CoreOS Container Linux or Flatcar Linux.
 
 We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create a VPC, gateway, subnets, security groups, controller instances, worker auto-scaling group, network load balancer, and TLS assets.
 
@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.
@@ -49,7 +49,7 @@ Configure the AWS provider to use your access key credentials in a `providers.tf
 
 ```tf
 provider "aws" {
-  version                 = "2.41.0"
+  version                 = "2.48.0"
   region                  = "eu-central-1"
   shared_credentials_file = "/home/user/.config/aws/credentials"
 }

docs/cl/azure.md

@@ -3,7 +3,7 @@
 !!! danger
     Typhoon for Azure is alpha. For production, use AWS, Google Cloud, or bare-metal. As Azure matures, check [errata](https://github.com/poseidon/typhoon/wiki/Errata) for known shortcomings.
 
-In this tutorial, we'll create a Kubernetes v1.17.3 cluster on Azure with Container Linux.
+In this tutorial, we'll create a Kubernetes v1.17.3 cluster on Azure with CoreOS Container Linux or Flatcar Linux.
 
 We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create a resource group, virtual network, subnets, security groups, controller availability set, worker scale set, load balancer, and TLS assets.
 
@@ -21,7 +21,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.
@@ -50,7 +50,7 @@ Configure the Azure provider in a `providers.tf` file.
 
 ```tf
 provider "azurerm" {
-  version = "1.38.0"
+  version = "1.43.0"
 }
 
 provider "ct" {

docs/cl/bare-metal.md

@@ -1,6 +1,6 @@
 # Bare-Metal
 
-In this tutorial, we'll network boot and provision a Kubernetes v1.17.3 cluster on bare-metal with Container Linux.
+In this tutorial, we'll network boot and provision a Kubernetes v1.17.3 cluster on bare-metal with CoreOS Container Linux or Flatcar Linux.
 
 First, we'll deploy a [Matchbox](https://github.com/poseidon/matchbox) service and setup a network boot environment. Then, we'll declare a Kubernetes cluster using the Typhoon Terraform module and power on machines. On PXE boot, machines will install Container Linux to disk, reboot into the disk install, and provision themselves as Kubernetes controllers or workers via Ignition.
 
@@ -111,7 +111,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-matchbox](https://github.com/poseidon/terraform-provider-matchbox) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.

docs/cl/digital-ocean.md

@@ -1,6 +1,6 @@
 # Digital Ocean
 
-In this tutorial, we'll create a Kubernetes v1.17.3 cluster on DigitalOcean with Container Linux.
+In this tutorial, we'll create a Kubernetes v1.17.3 cluster on DigitalOcean with CoreOS Container Linux or Flatcar Linux.
 
 We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create controller droplets, worker droplets, DNS records, tags, and TLS assets.
 
@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.
@@ -50,7 +50,7 @@ Configure the DigitalOcean provider to use your token in a `providers.tf` file.
 
 ```tf
 provider "digitalocean" {
-  version = "1.11.0"
+  version = "1.14.0"
   token = "${chomp(file("~/.config/digital-ocean/token"))}"
 }
 

docs/cl/google-cloud.md

@@ -1,6 +1,6 @@
 # Google Cloud
 
-In this tutorial, we'll create a Kubernetes v1.17.3 cluster on Google Compute Engine with Container Linux.
+In this tutorial, we'll create a Kubernetes v1.17.3 cluster on Google Compute Engine with CoreOS Container Linux or Flatcar Linux.
 
 We'll declare a Kubernetes cluster using the Typhoon Terraform module. Then apply the changes to create a network, firewall rules, health checks, controller instances, worker managed instance group, load balancers, and TLS assets.
 
@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.
@@ -49,7 +49,7 @@ Configure the Google Cloud provider to use your service account key, project-id,
 
 ```tf
 provider "google" {
-  version     = "3.4.0"
+  version     = "3.7.0"
   project     = "project-id"
   region      = "us-central1"
   credentials = file("~/.config/google-cloud/terraform.json")

docs/fedora-coreos/aws.md

@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.
@@ -49,7 +49,7 @@ Configure the AWS provider to use your access key credentials in a `providers.tf
 
 ```tf
 provider "aws" {
-  version                 = "2.41.0"
+  version                 = "2.48.0"
   region                  = "eu-central-1"
   shared_credentials_file = "/home/user/.config/aws/credentials"
 }

docs/fedora-coreos/bare-metal.md

@@ -111,7 +111,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-matchbox](https://github.com/poseidon/terraform-provider-matchbox) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.

docs/fedora-coreos/google-cloud.md

@@ -21,7 +21,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.16
+Terraform v0.12.20
 ```
 
 Add the [terraform-provider-ct](https://github.com/poseidon/terraform-provider-ct) plugin binary for your system to `~/.terraform.d/plugins/`, noting the final name.
@@ -52,7 +52,7 @@ Configure the Google Cloud provider to use your service account key, project-id,
 
 ```tf
 provider "google" {
-  version     = "3.4.0"
+  version     = "3.7.0"
   project     = "project-id"
   region      = "us-central1"
   credentials = file("~/.config/google-cloud/terraform.json")