docs: Add fix for KUBELET_EXTRA_ARGS overwrite to EKS managed node group example (#2150)

examples/eks_managed_node_group/README.md

@@ -34,6 +34,7 @@ When using the default AMI provided by the EKS Managed Node Group service (i.e.
     EOF
     # Source extra environment variables in bootstrap script
     sed -i '/^set -o errexit/a\\nsource /etc/profile.d/bootstrap.sh' /etc/eks/bootstrap.sh
+    sed -i 's/KUBELET_EXTRA_ARGS=$2/KUBELET_EXTRA_ARGS="$2 $KUBELET_EXTRA_ARGS"/' /etc/eks/bootstrap.sh
     EOT
   }
   ...