Add annotations docs for ingress controller (#1117)

* Add annotations docs for ingress controller

* Add ingress example

* Use yaml format

docs/04.Cloud-Native/4.1.Kubernetes-Ingress-Controller.md

@@ -7,6 +7,7 @@
  - [Handle Ingresses within Specified K8s Namespaces](#handle-ingresses-within-specified-k8s-namespaces)
  - [Use a Customized Ingress Class](#use-a-customized-ingress-class)
  - [Deploy Outside of a K8s Cluster](#deploy-outside-of-a-k8s-cluster)
+ - [Additional Annotations](#additional-annotations)
 
 The IngressController is an implementation of [Kubernetes ingress controller](https://kubernetes.io/docs/concepts/services-networking/ingress-controllers/), it watches Kubernetes Ingress, Service, Endpoints, and Secrets then translates them to Easegress HTTP server and pipelines.
 
@@ -201,3 +202,53 @@ httpServer:
  keepAliveTimeout: 60s
  maxConnections: 10240
 ```
+
+### Additional Annotations
+
+When defining your `Ingress` configurations, you can use the following `easegress` specific annotations for added customization:
+
+- **Load Balancing**: `easegress.ingress.kubernetes.io/proxy-load-balance`
+- **Header Hash Key for Load Balancing**: `easegress.ingress.kubernetes.io/proxy-header-hash-key`
+- **Forwarding Key**: `easegress.ingress.kubernetes.io/proxy-forward-key`
+- **Server Response Maximum Size**: `easegress.ingress.kubernetes.io/proxy-server-max-size`
+- **Proxy Timeout**: `easegress.ingress.kubernetes.io/proxy-timeout`
+
+Please refer to the [Proxy Server Pool Spec](../07.Reference/7.02.Filters.md#proxyserverpoolspec) and [Load Balance Spec](../07.Reference/7.02.Filters.md#proxyloadbalancespec) to get the details of the corresponding annotations.
+
+These annotations provide additional configurations to optimize the behavior and performance of your ingress controllers in different scenario.
+
+```yaml
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+ name: ingress-example
+ annotations:
+ easegress.ingress.kubernetes.io/proxy-load-balance: "ipHash"
+ easegress.ingress.kubernetes.io/proxy-header-hash-key: "X-User-Id"
+ easegress.ingress.kubernetes.io/proxy-forward-key: ""
+ easegress.ingress.kubernetes.io/proxy-server-max-size: "12400"
+ easegress.ingress.kubernetes.io/proxy-timeout: "10s"
+spec:
+ ingressClassName: easegress
+ rules:
+ - host: "www.example.com"
+ http:
+ paths:
+ - pathType: Prefix
+ path: /
+ backend:
+ service:
+ name: hello-service
+ port:
+ number: 60001
+ - host: "*.megaease.com"
+ http:
+ paths:
+ - pathType: Prefix
+ path: /
+ backend:
+ service:
+ name: hello-service
+ port:
+ number: 60002
+```