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

Author: dghubble

docs/cl/aws.md

@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.20
+Terraform v0.12.21
 ```
 
 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                 = "2.48.0"
+  version                 = "2.53.0"
   region                  = "eu-central-1"
   shared_credentials_file = "/home/user/.config/aws/credentials"
 }

docs/cl/azure.md

@@ -21,7 +21,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.20
+Terraform v0.12.21
 ```
 
 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 = "2.0.0"
+  version = "2.1.0"
 }
 
 provider "ct" {

docs/cl/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 v0.12.20
+Terraform v0.12.21
 ```
 
 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

@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.20
+Terraform v0.12.21
 ```
 
 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.

docs/cl/google-cloud.md

@@ -18,7 +18,7 @@ Install [Terraform](https://www.terraform.io/downloads.html) v0.12.6+ on your sy
 
 ```sh
 $ terraform version
-Terraform v0.12.20
+Terraform v0.12.21
 ```
 
 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     = "3.7.0"
+  version     = "3.12.0"
   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 v0.12.20
+Terraform v0.12.21
 ```
 
 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                 = "2.48.0"
+  version                 = "2.53.0"
   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 v0.12.20
+Terraform v0.12.21
 ```
 
 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 v0.12.20
+Terraform v0.12.21
 ```
 
 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     = "3.7.0"
+  version     = "3.12.0"
   project     = "project-id"
   region      = "us-central1"
   credentials = file("~/.config/google-cloud/terraform.json")