Separate documentation section for nested block.

Author: ewbankkit

website/docs/r/quicksight_key_registration.html.markdown

@@ -31,11 +31,14 @@ resource "aws_quicksight_key_registration" "example" {
 
 This resource supports the following arguments:
 
-* `key_registration` - (Required) Registered keys.
-    * `default_key` - (Optional) Whether the key is set as the default key for encryption and decryption use.
-    * `key_arn` - (Required) ARN of the AWS KMS key that is registered for encryption and decryption use.
+* `key_registration` - (Required) Registered keys. See [key_registration](#key_registration).
 * `region` - (Optional) Region where this resource will be [managed](https://docs.aws.amazon.com/general/latest/gr/rande.html#regional-endpoints). Defaults to the Region set in the [provider configuration](https://registry.terraform.io/providers/hashicorp/aws/latest/docs#aws-configuration-reference).
 
+### key_registration
+
+* `default_key` - (Optional) Whether the key is set as the default key for encryption and decryption use.
+* `key_arn` - (Required) ARN of the AWS KMS key that is registered for encryption and decryption use.
+
 ## Attribute Reference
 
 This resource exports the following attributes in addition to the arguments above: