docs: ingressClass (#1076)

* docs: ingressClass

* add link to proposal

docs/features/custom-ingress-class.md

@@ -0,0 +1,37 @@
+# Custom Ingress Class
+> **Minimum version:** 1.3.0
+
+Custom ingress class allows you to customize the ingress class selector that AGIC will use when filtering the ingress manifests. AGIC uses `azure/application-gateway` as default ingress class. This  will allow you to target multiple AGICs on a single namespace as each AGIC can now use it's own ingress class.
+
+For instance, AGIC with ingress class `agic-public` can serves public traffic, and AGIC wit `agic-private` can serve "internal" traffic.
+
+To use a custom ingress class,
+
+1. Install AGIC by providing a value for `kubernetes.ingressClass` in helm config.
+    ```bash
+    helm install ./helm/ingress-azure \
+        --name ingress-azure \
+        -f helm-config.yaml
+        --set kubernetes.ingressClass  arbitrary-class
+    ```
+
+2. Then, change your ingress manifest's  `kubernetes.io/ingress.class` annotation to match the value provided to AGIC.
+    ```yaml
+    kind: Ingress
+    metadata:
+    name: go-server-ingress-affinity
+    namespace: test-ag
+    annotations:
+        kubernetes.io/ingress.class: arbitrary-class
+    spec:
+    rules:
+    - http:
+        paths:
+        - path: /hello/
+            backend:
+            serviceName: go-server-service
+            servicePort: 80
+    ```
+
+## Reference
+* [Proposal Document](../../proposals\multiple-gateways-single-cluster.md)

docs/helm-values-documenation.md

@@ -17,6 +17,7 @@
 | `kubernetes.nodeSelector` | `{}` | Scheduling node selector |
 | `kubernetes.tolerations` | `[]` | Scheduling tolerations |
 | `kubernetes.affinity` | `{}` | Scheduling affinity |
+| `kubernetes.ingressClass` | `azure/application-gateway` | Specify a [custom ingress class](features\custom-ingress-class.md) which will be used to match `kubernetes.io/ingress.class` in ingress manifest |
 | `rbac.enabled` | false | Specify true if kubernetes cluster is rbac enabled |
 | `armAuth.type` | | could be `aadPodIdentity` or `servicePrincipal` |
 | `armAuth.identityResourceID` | | Resource ID of the Azure Managed Identity |