docs: add EKS Auto Mode section to README.yaml

Port the EKS Auto Mode documentation from README.md back to README.yaml
so it persists through readme generation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Benbentwo

README.yaml

@@ -328,5 +328,71 @@ usage: |-
   > many issues you may read about that had affected prior versions. See the version 2 README and release notes
   > for more information on the challenges and workarounds that were required prior to v3.
 
+  ## EKS Auto Mode
+
+  This module supports [EKS Auto Mode](https://docs.aws.amazon.com/eks/latest/userguide/automode.html) (GA December 2024),
+  which delegates compute, networking, and storage management to AWS. Enable it using the `auto_mode_compute_config`,
+  `auto_mode_storage_config`, and `auto_mode_elastic_load_balancing` variables.
+
+  ### Enabling Auto Mode
+
+  ```hcl
+  module "eks_cluster" {
+    source  = "cloudposse/eks-cluster/aws"
+    # version = "..."
+
+    auto_mode_compute_config = {
+      enabled       = true
+      node_pools    = ["general-purpose", "system"]
+      node_role_arn = aws_iam_role.auto_mode_node.arn
+    }
+
+    auto_mode_storage_config = {
+      block_storage = {
+        enabled = true
+      }
+    }
+
+    auto_mode_elastic_load_balancing = {
+      enabled = true
+    }
+
+    # ... other configuration
+  }
+  ```
+
+  When Auto Mode is enabled, this module automatically:
+  - Sets `bootstrap_self_managed_addons = false` (unless explicitly overridden)
+  - Adds `sts:TagSession` to the cluster IAM role trust policy
+  - Attaches 4 additional IAM policies to the cluster role: `AmazonEKSComputePolicy`, `AmazonEKSBlockStoragePolicy`,
+    `AmazonEKSLoadBalancingPolicy`, and `AmazonEKSNetworkingPolicy`
+
+  ### Capabilities
+
+  All three capabilities must be enabled or disabled together:
+
+  | Capability | Variable | What AWS Manages |
+  |-----------|----------|-----------------|
+  | **Compute** | `auto_mode_compute_config` | Node provisioning via managed Karpenter |
+  | **Storage** | `auto_mode_storage_config` | EBS volumes via `ebs.csi.eks.amazonaws.com` |
+  | **Networking** | `auto_mode_elastic_load_balancing` | ALB/NLB for Services and Ingress |
+
+  ### Important Notes
+
+  - Requires AWS provider `>= 5.79.0` and Kubernetes `>= 1.29`
+  - Auto Mode manages `vpc-cni`, `kube-proxy`, `coredns`, and `aws-ebs-csi-driver` add-ons automatically.
+    Do not include these in the `addons` variable when Auto Mode is enabled.
+  - Auto Mode nodes are Bottlerocket-only, immutable, with no SSH/IMDS access
+  - Nodes have a 21-day maximum lifetime and are automatically rotated
+  - The `node_role_arn` in `auto_mode_compute_config` must be an IAM role with
+    `AmazonEKSWorkerNodeMinimalPolicy` and `AmazonEC2ContainerRegistryPullOnly` attached
+
+  ### Cluster Version Upgrades
+
+  With Auto Mode, Kubernetes version upgrades are simplified:
+  1. Bump `kubernetes_version` and apply -- control plane upgrades in place
+  2. Managed Karpenter detects version drift and automatically replaces nodes
+  3. Auto Mode-managed add-ons are automatically upgraded to compatible versions
+
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