Add ingress.kubernetes.io/proxy-next-upstream annotation to annotations.md
Add ingress.kubernetes.io/proxy-next-upstream annotation to annotations.md

kubernetes/ingress-nginx,kubernetes/ingress-nginx,canhnt/ingress,nicksardo/ingress,nicksardo/ingress,caicloud/ingress,jcmoraisjr/ingress,danielqsj/ingress,caicloud/ingress,nicksardo/ingress,kubernetes/ingress-nginx,jcmoraisjr/ingress,canhnt/ingress,canhnt/ingress,aledbf/ingress-nginx,canhnt/ingress,aledbf/ingress-nginx,aledbf/ingress-nginx,jcmoraisjr/ingress,chentao1596/ingress,nicksardo/ingress,caicloud/ingress,chentao1596/ingress,kubernetes/ingress-nginx,aledbf/ingress-nginx,danielqsj/ingress,caicloud/ingress,kubernetes/ingress-nginx