doc: update go version to v1.20

Author: yyy1000

CONTRIBUTING.md

@@ -10,7 +10,7 @@ Please see https://git.k8s.io/community/CLA.md for more info.
 
 ## Prerequisites
 
-- [go](https://golang.org/dl/) version v1.16+.
+- [go](https://golang.org/dl/) version v1.20+.
 - [docker](https://docs.docker.com/install/) version 17.03+.
 - [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) version v1.11.3+.
 - [kustomize](https://github.com/kubernetes-sigs/kustomize/blob/master/site/content/en/docs/Getting%20started/installation.md) v3.1.0+

docs/book/src/quick-start.md

@@ -9,7 +9,7 @@ This Quick Start guide will cover:
 
 ## Prerequisites
 
-- [go](https://golang.org/dl/) version v1.19.0+
+- [go](https://golang.org/dl/) version v1.20.0+
 - [docker](https://docs.docker.com/install/) version 17.03+.
 - [kubectl](https://kubernetes.io/docs/tasks/tools/install-kubectl/) version v1.11.3+.
 - Access to a Kubernetes v1.11.3+ cluster.