Add terraform-docs (#10)

* Add terraform-docs

* Update Makefile

install/Makefile

@@ -23,6 +23,7 @@ all: aws-vault \
 	 kubens \
 	 sops \
 	 terraform \
+	 terraform-docs \
 	 terragrunt \
 	 yq
 
@@ -141,6 +142,11 @@ terraform:
 	mv $(TMP)/$@/terraform $(INSTALL_PATH)/$@
 	chmod +x $(INSTALL_PATH)/$@
 
+export TERRAFORM_DOCS_VERSION ?= 0.3.0
+## Install terraform-docs to generate docs from terraform modules
+terraform-docs:
+	$(call github_download_binary_release,segmentio,v$(TERRAFORM_DOCS_VERSION),$@_$(OS)_$(ARCH))
+
 export TERRAGRUNT_VERSION ?= 0.14.7
 ## Install terragrunt for tools that make it easier to work with multiple Terraform modules
 terragrunt: