Include instructions on how to reach Couchbase UI w/ Couchbase Operator + Minikube

After deploying Couchbase to kubernetes (via the operator), there doesn't see to be any clear instructions on how to reach the Couchbase UI when using it for developer purposes.

There are a few known ways:

• minikube service cb-example-ui
• kubectl port-forward cb-example-0000 8091:8091

This seems like a place where users will be commonly tripped up, and some hints in the docs will save them some headache and forums questions.