fixed iris sklearn model example (#3762)

* fixed tunnel 

fixed the tunnel issue, as no 80 port running inside the pod. Tunnel should be created on ingress gateway service

* updated the Port-Forwarding step

* updated port-forwarding options with Istio svc

* fixed types

* fixed indentation issue

* removed --address field

examples/models/sklearn_iris/sklearn_iris.ipynb

@@ -33,7 +33,8 @@
     "Then port-forward to that ingress on localhost:8003 in a separate terminal either with:\n",
     "\n",
     " * Ambassador: `kubectl port-forward $(kubectl get pods -n seldon-system -l app.kubernetes.io/name=ambassador -o jsonpath='{.items[0].metadata.name}') -n seldon-system 8003:8080`\n",
-    " * Istio: `kubectl port-forward $(kubectl get pods -l istio=ingressgateway -n istio-system -o jsonpath='{.items[0].metadata.name}') -n istio-system 8003:80`"
+    " * Istio: `kubectl port-forward $(kubectl get pods -l istio=ingressgateway -n istio-system -o jsonpath='{.items[0].metadata.name}') -n istio-system 8003:8080`\n",
+    " * Istio: `kubectl port-forward  -n istio-system svc/istio-ingressgateway 8003:80`"
    ]
   },
   {