docs(gateway): add prerequisites

Author: duanhongyi

README.md

@@ -1,9 +1,15 @@
-# Drycc Gateway
+# Gateway
 
 [![Build Status](https://woodpecker.drycc.cc/api/badges/drycc/gateway/status.svg)](https://woodpecker.drycc.cc/drycc/gateway)
 
 Drycc (pronounced DAY-iss) Workflow is an open source Platform as a Service (PaaS) that adds a developer-friendly layer to any [Kubernetes](http://kubernetes.io) cluster, making it easy to deploy and manage applications on your own servers.
 
+## Prerequisites
+
+- Kubernetes 1.19+
+- Helm 3.2.0+
+- Gateway API 0.5.1+
+
 ## Description
 
-This is a gateway chart that integrates cert-manager. Gateway API is an open source project managed by the [SIG-NETWORK](https://github.com/kubernetes-sigs/gateway-api) community. It is a collection of resources that model service networking in Kubernetes. These resources - GatewayClass, Gateway, HTTPRoute, TCPRoute, Service, etc - aim to evolve Kubernetes service networking through expressive, extensible, and role-oriented interfaces that are implemented by many vendors and have broad industry support.
+Drycc Gateway is a gateway chart that integrates cert-manager.