README should describe dependence on .wskprops

Even though we build the CLI into our binary, we still make use of .wskprops. We should describe how (and in what priority order) we get APIHOST and AUTH values. To get values from .wskprops, we of course need to have the CLI in order for it to create this file and "set" these values.

This new section should go BEFORE we talk about "deploying the triggerrule test case:" which we have 2 methods to run (Go and Binary); this means we likely need to have another markdown file we link in both places (or before both) to describe thee details but not distract people who already have done CLI setup, etc.

Start with the README and the sections around "deploying the triggerrule test case," including both the Go and Binary methods. Trace how APIHOST and AUTH are obtained, including the priority order and the role of .wskprops, then document those details before the test-case instructions or in a linked Markdown section. Done means both paths point to clear setup guidance without distracting users who already completed CLI setup.

Written by the indexing model from the issue text.