Update Netlify link address

Author: jihoon-seo

README.md

@@ -1,6 +1,6 @@
 # The Kubernetes documentation
 
-[![Netlify Status](https://api.netlify.com/api/v1/badges/be93b718-a6df-402a-b4a4-855ba186c97d/deploy-status)](https://app.netlify.com/sites/kubernetes-io-master-staging/deploys) [![GitHub release](https://img.shields.io/github/release/kubernetes/website.svg)](https://github.com/kubernetes/website/releases/latest)
+[![Netlify Status](https://api.netlify.com/api/v1/badges/be93b718-a6df-402a-b4a4-855ba186c97d/deploy-status)](https://app.netlify.com/sites/kubernetes-io-main-staging/deploys) [![GitHub release](https://img.shields.io/github/release/kubernetes/website.svg)](https://github.com/kubernetes/website/releases/latest)
 
 This repository contains the assets required to build the [Kubernetes website and documentation](https://kubernetes.io/). We're glad that you want to contribute!