feat: Support additional cluster DNS IPs with Bottlerocket based AMIs (#3051)

* Support adding additional cluster dns ranges to bottlerocket template

* Add example for multiple dns ips

* fmt, and tf docs

* fix: Use a list by default for cluster-dns-ip

---------

Co-authored-by: Bryant Biggs <bryantbiggs@gmail.com>

modules/_user_data/README.md

@@ -36,6 +36,7 @@ No modules.
 
 | Name | Description | Type | Default | Required |
 |------|-------------|------|---------|:--------:|
+| <a name="input_additional_cluster_dns_ips"></a> [additional\_cluster\_dns\_ips](#input\_additional\_cluster\_dns\_ips) | Additional DNS IP addresses to use for the cluster. Only used when `ami_type` = `BOTTLEROCKET_*` | `list(string)` | `[]` | no |
 | <a name="input_ami_type"></a> [ami\_type](#input\_ami\_type) | Type of Amazon Machine Image (AMI) associated with the EKS Node Group. See the [AWS documentation](https://docs.aws.amazon.com/eks/latest/APIReference/API_Nodegroup.html#AmazonEKS-Type-Nodegroup-amiType) for valid values | `string` | `null` | no |
 | <a name="input_bootstrap_extra_args"></a> [bootstrap\_extra\_args](#input\_bootstrap\_extra\_args) | Additional arguments passed to the bootstrap script. When `ami_type` = `BOTTLEROCKET_*`; these are additional [settings](https://github.com/bottlerocket-os/bottlerocket#settings) that are provided to the Bottlerocket user data | `string` | `""` | no |
 | <a name="input_cloudinit_post_nodeadm"></a> [cloudinit\_post\_nodeadm](#input\_cloudinit\_post\_nodeadm) | Array of cloud-init document parts that are created after the nodeadm document part | <pre>list(object({<br>    content      = string<br>    content_type = optional(string)<br>    filename     = optional(string)<br>    merge_type   = optional(string)<br>  }))</pre> | `[]` | no |