docs/resource/aws_eks_node_group: Note max items restriction for inst…

…ance_types argument (#11457)

Reference: #11414

website/docs/r/eks_node_group.html.markdown

@@ -103,7 +103,7 @@ The following arguments are optional:
 
 * `ami_type` - (Optional) Type of Amazon Machine Image (AMI) associated with the EKS Node Group. Defaults to `AL2_x86_64`. Valid values: `AL2_x86_64`, `AL2_x86_64_GPU`. Terraform will only perform drift detection if a configuration value is provided.
 * `disk_size` - (Optional) Disk size in GiB for worker nodes. Defaults to `20`. Terraform will only perform drift detection if a configuration value is provided.
-* `instance_types` - (Optional) Set of instance types associated with the EKS Node Group. Defaults to `["t3.medium"]`. Terraform will only perform drift detection if a configuration value is provided.
+* `instance_types` - (Optional) Set of instance types associated with the EKS Node Group. Defaults to `["t3.medium"]`. Terraform will only perform drift detection if a configuration value is provided. Currently, the EKS API only accepts a single value in the set.
 * `labels` - (Optional) Key-value mapping of Kubernetes labels. Only labels that are applied with the EKS API are managed by this argument. Other Kubernetes labels applied to the EKS Node Group will not be managed.
 * `release_version` – (Optional) AMI version of the EKS Node Group. Defaults to latest version for Kubernetes version.
 * `remote_access` - (Optional) Configuration block with remote access settings. Detailed below.