docs: Add note on kms_key_id description to use the full ARN and not an alias (#455)

Resolves undefined

Author: rsmets

README.md

@@ -278,7 +278,7 @@ Users have the ability to:
 | <a name="input_instance_class"></a> [instance\_class](#input\_instance\_class) | The instance type of the RDS instance | `string` | `null` | no |
 | <a name="input_instance_use_identifier_prefix"></a> [instance\_use\_identifier\_prefix](#input\_instance\_use\_identifier\_prefix) | Determines whether to use `identifier` as is or create a unique identifier beginning with `identifier` as the specified prefix | `bool` | `false` | no |
 | <a name="input_iops"></a> [iops](#input\_iops) | The amount of provisioned IOPS. Setting this implies a storage\_type of 'io1' | `number` | `0` | no |
-| <a name="input_kms_key_id"></a> [kms\_key\_id](#input\_kms\_key\_id) | The ARN for the KMS encryption key. If creating an encrypted replica, set this to the destination KMS ARN. If storage\_encrypted is set to true and kms\_key\_id is not specified the default KMS key created in your account will be used | `string` | `null` | no |
+| <a name="input_kms_key_id"></a> [kms\_key\_id](#input\_kms\_key\_id) | The ARN for the KMS encryption key. If creating an encrypted replica, set this to the destination KMS ARN. If storage\_encrypted is set to true and kms\_key\_id is not specified the default KMS key created in your account will be used. Be sure to use the full ARN, not a key alias. | `string` | `null` | no |
 | <a name="input_license_model"></a> [license\_model](#input\_license\_model) | License model information for this DB instance. Optional, but required for some DB engines, i.e. Oracle SE1 | `string` | `null` | no |
 | <a name="input_maintenance_window"></a> [maintenance\_window](#input\_maintenance\_window) | The window to perform maintenance in. Syntax: 'ddd:hh24:mi-ddd:hh24:mi'. Eg: 'Mon:00:00-Mon:03:00' | `string` | `null` | no |
 | <a name="input_major_engine_version"></a> [major\_engine\_version](#input\_major\_engine\_version) | Specifies the major version of the engine that this option group should be associated with | `string` | `null` | no |

variables.tf

@@ -34,7 +34,7 @@ variable "storage_encrypted" {
 }
 
 variable "kms_key_id" {
-  description = "The ARN for the KMS encryption key. If creating an encrypted replica, set this to the destination KMS ARN. If storage_encrypted is set to true and kms_key_id is not specified the default KMS key created in your account will be used"
+  description = "The ARN for the KMS encryption key. If creating an encrypted replica, set this to the destination KMS ARN. If storage_encrypted is set to true and kms_key_id is not specified the default KMS key created in your account will be used. Be sure to use the full ARN, not a key alias."
   type        = string
   default     = null
 }