Make 1.16 as default

[sayboras]

Description

Fixes #2175

Testing

create new cluster

$ ./eksctl create cluster --managed --node-private-networking               
[ℹ]  eksctl version 0.21.0-dev+f17aff04.2020-05-16T14:42:34Z
[ℹ]  using region us-east-2
[ℹ]  setting availability zones to [us-east-2a us-east-2b us-east-2c]
[ℹ]  subnets for us-east-2a - public:192.168.0.0/19 private:192.168.96.0/19
[ℹ]  subnets for us-east-2b - public:192.168.32.0/19 private:192.168.128.0/19
[ℹ]  subnets for us-east-2c - public:192.168.64.0/19 private:192.168.160.0/19
[ℹ]  using Kubernetes version 1.16
[ℹ]  creating EKS cluster "exciting-outfit-1589604182" in "us-east-2" region with managed nodes
[ℹ]  will create 2 separate CloudFormation stacks for cluster itself and the initial managed nodegroup
[ℹ]  if you encounter any issues, check CloudFormation console or try 'eksctl utils describe-stacks --region=us-east-2 --cluster=exciting-outfit-1589604182'
[ℹ]  CloudWatch logging will not be enabled for cluster "exciting-outfit-1589604182" in "us-east-2"
[ℹ]  you can enable it with 'eksctl utils update-cluster-logging --region=us-east-2 --cluster=exciting-outfit-1589604182'
[ℹ]  Kubernetes API endpoint access will use default of {publicAccess=true, privateAccess=false} for cluster "exciting-outfit-1589604182" in "us-east-2"
[ℹ]  2 sequential tasks: { create cluster control plane "exciting-outfit-1589604182", 2 parallel sub-tasks: { no tasks, create managed nodegroup "ng-2844eacf" } }
[ℹ]  building cluster stack "eksctl-exciting-outfit-1589604182-cluster"
[ℹ]  deploying stack "eksctl-exciting-outfit-1589604182-cluster"
[ℹ]  building managed nodegroup stack "eksctl-exciting-outfit-1589604182-nodegroup-ng-2844eacf"
[ℹ]  deploying stack "eksctl-exciting-outfit-1589604182-nodegroup-ng-2844eacf"
[ℹ]  waiting for the control plane availability...
[✔]  saved kubeconfig as "/home/tammach/.kube/config"
[ℹ]  no tasks
[✔]  all EKS cluster resources for "exciting-outfit-1589604182" have been created
[ℹ]  nodegroup "ng-2844eacf" has 2 node(s)
[ℹ]  node "ip-192-168-185-172.us-east-2.compute.internal" is ready
[ℹ]  node "ip-192-168-96-62.us-east-2.compute.internal" is ready
[ℹ]  waiting for at least 2 node(s) to become ready in "ng-2844eacf"
[ℹ]  nodegroup "ng-2844eacf" has 2 node(s)
[ℹ]  node "ip-192-168-185-172.us-east-2.compute.internal" is ready
[ℹ]  node "ip-192-168-96-62.us-east-2.compute.internal" is ready
[ℹ]  kubectl command should work with "/home/tammach/.kube/config", try 'kubectl get nodes'
[✔]  EKS cluster "exciting-outfit-1589604182" in "us-east-2" region is ready

$ kgno
NAME                                            STATUS   ROLES    AGE   VERSION
ip-192-168-185-172.us-east-2.compute.internal   Ready    <none>   24m   v1.16.8-eks-e16311
ip-192-168-96-62.us-east-2.compute.internal     Ready    <none>   24m   v1.16.8-eks-e16311

Checklist

• Added tests that cover your change (if possible)
• Added/modified documentation as required (such as the README.md, or the userdocs directory)
• Manually tested
• Added labels for change area (e.g. area/nodegroup), target version (e.g. version/0.12.0) and kind (e.g. kind/improvement)
• Make sure the title of the PR is a good description that can go into the release notes