fix(multi-runner): Add missing default for runner_metadata_options (#2690)

Author: npalm

README.md

@@ -443,7 +443,7 @@ We welcome any improvement to the standard module to make the default as secure
 | <a name="input_ami_owners"></a> [ami\_owners](#input\_ami\_owners) | The list of owners used to select the AMI of action runner instances. | `list(string)` | <pre>[<br>  "amazon"<br>]</pre> | no |
 | <a name="input_aws_partition"></a> [aws\_partition](#input\_aws\_partition) | (optiona) partition in the arn namespace to use if not 'aws' | `string` | `"aws"` | no |
 | <a name="input_aws_region"></a> [aws\_region](#input\_aws\_region) | AWS region. | `string` | n/a | yes |
-| <a name="input_block_device_mappings"></a> [block\_device\_mappings](#input\_block\_device\_mappings) | The EC2 instance block device configuration. Takes the following keys: `device_name`, `delete_on_termination`, `volume_type`, `volume_size`, `encrypted`, `iops`, `throughput`, `kms_key_id`, `snapshot_id`. | <pre>list(object({<br>    delete_on_termination = bool<br>    device_name           = string<br>    encrypted             = bool<br>    iops                  = number<br>    kms_key_id            = string<br>    snapshot_id           = string<br>    throughput            = number<br>    volume_size           = number<br>    volume_type           = string<br>  }))</pre> | <pre>[<br>  {<br>    "delete_on_termination": true,<br>    "device_name": "/dev/xvda",<br>    "encrypted": true,<br>    "iops": null,<br>    "kms_key_id": null,<br>    "snapshot_id": null,<br>    "throughput": null,<br>    "volume_size": 30,<br>    "volume_type": "gp3"<br>  }<br>]</pre> | no |
+| <a name="input_block_device_mappings"></a> [block\_device\_mappings](#input\_block\_device\_mappings) | The EC2 instance block device configuration. Takes the following keys: `device_name`, `delete_on_termination`, `volume_type`, `volume_size`, `encrypted`, `iops`, `throughput`, `kms_key_id`, `snapshot_id`. | <pre>list(object({<br>    delete_on_termination = optional(bool, true)<br>    device_name           = optional(string, "/dev/xvda")<br>    encrypted             = optional(bool, true)<br>    iops                  = optional(number)<br>    kms_key_id            = optional(string)<br>    snapshot_id           = optional(string)<br>    throughput            = optional(number)<br>    volume_size           = number<br>    volume_type           = optional(string, "gp3")<br>  }))</pre> | <pre>[<br>  {<br>    "volume_size": 30<br>  }<br>]</pre> | no |
 | <a name="input_cloudwatch_config"></a> [cloudwatch\_config](#input\_cloudwatch\_config) | (optional) Replaces the module default cloudwatch log config. See https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch-Agent-Configuration-File-Details.html for details. | `string` | `null` | no |
 | <a name="input_create_service_linked_role_spot"></a> [create\_service\_linked\_role\_spot](#input\_create\_service\_linked\_role\_spot) | (optional) create the serviced linked role for spot instances that is required by the scale-up lambda. | `bool` | `false` | no |
 | <a name="input_delay_webhook_event"></a> [delay\_webhook\_event](#input\_delay\_webhook\_event) | The number of seconds the event accepted by the webhook is invisible on the queue before the scale up lambda will receive the event. | `number` | `30` | no |