docs: added argument details for tfe_test_variable

Author: quixoticmonk

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ENHANCEMENTS:
 * `r/tfe_oauth_client`: The `oauth_token` attribute no longer triggers resource replacement unless combined with other replacement-triggering attributes. Use `terraform apply -replace` to force replacement. By @lilincmu [#1825](https://github.com/hashicorp/terraform-provider-tfe/pull/1825)
+* `r/tfe_test_variable`: Add missing argument reference and attributes documentation ([#1625](https://github.com/hashicorp/terraform-provider-tfe/issues/1625))
 
 FEATURES:
 * `r/tfe_registry_module`: Add `source_directory` and `tag_prefix` registry module support for private registry monorepository, which is a beta feature and not available to all users, by @jillirami ([#1800](https://github.com/hashicorp/terraform-provider-tfe/pull/1800))

website/docs/r/tfe_test_variable.html.markdown

@@ -51,3 +51,25 @@ resource "tfe_test_variable" "tf_test_test_variable" {
 ```
 
 -> **Note:** Write-Only argument `value_wo` is available to use in place of `value`. Write-Only arguments are supported in HashiCorp Terraform 1.11.0 and later. [Learn more](https://developer.hashicorp.com/terraform/language/v1.11.x/resources/ephemeral#write-only-arguments).
+
+## Argument Reference
+
+The following arguments are supported:
+
+* `key` - (Required) Name of the variable.
+* `value` - (Optional) Value of the variable. Defaults to `""`. Cannot be used with `value_wo`.
+* `value_wo` - (Optional) Value of the variable in write-only mode. Cannot be used with `value`.
+* `category` - (Required) Whether this is a Terraform or environment variable. Valid values are `"env"`.
+* `description` - (Optional) Description of the variable. Defaults to `""`.
+* `hcl` - (Optional) Whether to evaluate the value of the variable as a string of HCL code. Defaults to `false`.
+* `sensitive` - (Optional) Whether the value is sensitive. Defaults to `false`.
+* `organization` - (Required) Name of the organization.
+* `module_name` - (Required) Name of the registry module.
+* `module_provider` - (Required) The provider of the registry module.
+
+## Attributes Reference
+
+In addition to all arguments above, the following attributes are exported:
+
+* `id` - The ID of the variable.
+* `readable_value` - A non-sensitive read-only copy of the variable value, which can be viewed or referenced in plan outputs without being redacted. Will only be present if the variable is not sensitive.