diff --git a/.gitignore b/.gitignore
index 7a3e2fd..5adf725 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,9 @@
 # Local .terraform directories
 **/.terraform/*
 
+# Terraform lockfile
+.terraform.lock.hcl
+
 # .tfstate files
 *.tfstate
 *.tfstate.*
diff --git a/README.md b/README.md
index b2712a2..d01467a 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,45 @@
 # terraform-aws-sso-assignment
 
 Terraform module which creates AWS SSO assignments on AWS.
+
+<!-- BEGINNING OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
+## Requirements
+
+| Name | Version |
+|------|---------|
+| <a name="requirement_terraform"></a> [terraform](#requirement\_terraform) | >= 0.13.7 |
+| <a name="requirement_aws"></a> [aws](#requirement\_aws) | >= 3.24.0 |
+
+## Providers
+
+| Name | Version |
+|------|---------|
+| <a name="provider_aws"></a> [aws](#provider\_aws) | 3.52.0 |
+
+## Modules
+
+No modules.
+
+## Resources
+
+| Name | Type |
+|------|------|
+| [aws_ssoadmin_account_assignment.groups](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/ssoadmin_account_assignment) | resource |
+| [aws_ssoadmin_account_assignment.users](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/ssoadmin_account_assignment) | resource |
+| [aws_identitystore_group.groups](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/identitystore_group) | data source |
+| [aws_identitystore_user.users](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/identitystore_user) | data source |
+| [aws_ssoadmin_permission_set.permission_sets](https://registry.terraform.io/providers/hashicorp/aws/latest/docs/data-sources/ssoadmin_permission_set) | data source |
+
+## Inputs
+
+| Name | Description | Type | Default | Required |
+|------|-------------|------|---------|:--------:|
+| <a name="input_assignments"></a> [assignments](#input\_assignments) | Configuration variable for account assignments. | `map(map(map(list(string))))` | n/a | yes |
+| <a name="input_identity_store_id"></a> [identity\_store\_id](#input\_identity\_store\_id) | The Identity Store ID associated with the Single Sign-On Instance. | `string` | n/a | yes |
+| <a name="input_instance_arn"></a> [instance\_arn](#input\_instance\_arn) | The Amazon Resource Name (ARN) of the SSO Instance under which the operation will be executed. | `string` | n/a | yes |
+| <a name="input_organization_accounts"></a> [organization\_accounts](#input\_organization\_accounts) | List of information of accounts which belongs to AWS Organizations. | <pre>list(object({<br>    arn   = string<br>    email = string<br>    id    = string<br>    name  = string<br>  }))</pre> | n/a | yes |
+
+## Outputs
+
+No outputs.
+<!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
diff --git a/variables.tf b/variables.tf
index 49e2eb2..2de8e1f 100644
--- a/variables.tf
+++ b/variables.tf
@@ -1,9 +1,11 @@
 variable "instance_arn" {
-  type = string
+  type        = string
+  description = "The Amazon Resource Name (ARN) of the SSO Instance under which the operation will be executed."
 }
 
 variable "identity_store_id" {
-  type = string
+  type        = string
+  description = "The Identity Store ID associated with the Single Sign-On Instance."
 }
 
 variable "organization_accounts" {
@@ -13,8 +15,10 @@ variable "organization_accounts" {
     id    = string
     name  = string
   }))
+  description = "List of information of accounts which belongs to AWS Organizations."
 }
 
 variable "assignments" {
-  type = map(map(map(list(string))))
+  type        = map(map(map(list(string))))
+  description = "Configuration variable for account assignments."
 }
diff --git a/versions.tf b/versions.tf
index e5dd90c..bc39f0a 100644
--- a/versions.tf
+++ b/versions.tf
@@ -1,4 +1,6 @@
 terraform {
+  required_version = ">= 0.13.7"
+
   required_providers {
     aws = {
       source  = "hashicorp/aws"