Merge pull request #122 from terraform-google-modules/internal/update-terraform-docs-required-version

Update documented version of `terraform-docs` to 0.6.0 to comply with the rest of CFT modules

Author: morgante

README.md

@@ -219,7 +219,7 @@ The root module is generated by running `make generate`. Changes to this reposit
 ### Requirements
 - [bundler](https://github.com/bundler/bundler)
 - [gcloud](https://cloud.google.com/sdk/install)
-- [terraform-docs](https://github.com/segmentio/terraform-docs/releases) 0.3.0
+- [terraform-docs](https://github.com/segmentio/terraform-docs/releases) 0.6.0
 
 ### Autogeneration of documentation from .tf files
 Run

autogen/README.md

@@ -166,7 +166,7 @@ The root module is generated by running `make generate`. Changes to this reposit
 ### Requirements
 - [bundler](https://github.com/bundler/bundler)
 - [gcloud](https://cloud.google.com/sdk/install)
-- [terraform-docs](https://github.com/segmentio/terraform-docs/releases) 0.3.0
+- [terraform-docs](https://github.com/segmentio/terraform-docs/releases) 0.6.0
 
 ### Autogeneration of documentation from .tf files
 Run

modules/private-cluster/README.md

@@ -8,7 +8,6 @@ The resources/services/activations/deletions that this module will create/trigge
 - Activate network policy if `network_policy` is true
 - Add `ip-masq-agent` configmap with provided `non_masquerade_cidrs` if `network_policy` is true
 
-
 **Note**: You must run Terraform from a VM on the same VPC as your cluster, otherwise there will be issues connecting to the GKE master.
 
 ## Usage
@@ -228,7 +227,7 @@ The root module is generated by running `make generate`. Changes to this reposit
 ### Requirements
 - [bundler](https://github.com/bundler/bundler)
 - [gcloud](https://cloud.google.com/sdk/install)
-- [terraform-docs](https://github.com/segmentio/terraform-docs/releases) 0.3.0
+- [terraform-docs](https://github.com/segmentio/terraform-docs/releases) 0.6.0
 
 ### Autogeneration of documentation from .tf files
 Run