I have followed the link which you have attached and it works as expected.
Here is a command which you can use:
minikube service hello-minikube --url
You will get a url like http://192.168.99.100:32382/ - the port and IP could and will change for you. Also note that the exposed port will be a random port like the 32382 and not 8080 that the pod uses.
Use the url in your browser, say and you should be able to see the output of the service.
I hope the information would be helpful for you.