Add nginx ingress controller example configuration (#48)

docs/resources/cluster.md

@@ -26,6 +26,43 @@ resource "kind_cluster" "default" {
 }
 ```
 
+To configure the cluster for nginx's ingress controller based on [kind's docs](https://kind.sigs.k8s.io/docs/user/ingress/):
+
+```hcl
+provider "kind" {}
+
+resource "kind_cluster" "default" {
+    name           = "test-cluster"
+    wait_for_ready = true
+
+  kind_config {
+      kind        = "Cluster"
+      api_version = "kind.x-k8s.io/v1alpha4"
+
+      node {
+          role = "control-plane"
+
+          kubeadm_config_patches = [
+              "kind: InitConfiguration\nnodeRegistration:\n  kubeletExtraArgs:\n    node-labels: \"ingress-ready=true\"\n"
+          ]
+
+          extra_port_mappings {
+              container_port = 80
+              host_port      = 80
+          }
+          extra_port_mappings {
+              container_port = 443
+              host_port      = 443
+          }
+      }
+
+      node {
+          role = "worker"
+      }
+  }
+}
+```
+
 To override the default kind config:
 
 ```hcl