I am trying to create a cluster with managed node spot instance using config file the below yml configuration but getting error

Error: loading config file “cluster-config.yaml”: error unmarshaling JSON: while decoding JSON: json: unknown field “instancesDistribution”

cluster-config.yaml

apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig

metadata:
  name: tk-cluster
  region: us-east-1

vpc:
  subnets:
    private:
      us-east-1a:
        id: subnet-023343e592c60f5a2
      us-east-1b:
        id: subnet-0fa6503c31bc4f10d
    public:
      us-east-1a:
        id: subnet-0b34dda879cce4239
      us-east-1b:
        id: subnet-099318b994c9d844f

managedNodeGroups:
  - name: ng-capacity-optimized
    minSize: 2
    maxSize: 5
    privateNetworking: false
    instancesDistribution:
      maxPrice: 0.017
      instanceTypes: ["t3.small", "t3.medium"] # At least one instance type should be specified
      onDemandBaseCapacity: 0
      onDemandPercentageAboveBaseCapacity: 50
      spotAllocationStrategy: "capacity-optimized"