Add note about external loadbalancer in the tutorial

[kdubois]

In https://redhat-scholars.github.io/kubernetes-tutorial/kubernetes-tutorial/kubectl.html we are using

kubectl expose deployment myapp --port=8080 --type=LoadBalancer

This is dependent on the IP availability from an external cloud provider.
We should add a note and also add the openshift route alternative eg.

oc create service clusterip myapp --tcp=80:8080 oc create route edge --service myapp --insecure-policy=Redirect