Reorganize README.md KinD example to make it more of a Getting Started guide

[diverdane]

Is your feature request related to a problem? Please describe.

Project management gave us some great suggestions re. the README.md for the
authn-k8s on KinD example. The suggestions were basically to make the
README.md more of a guided tour or a "Getting Started" guide.

The biggest part of this is to have the user jump into running the demo
right away, and then add background information about what the demo
scripts accomplished afterwards.

Describe the solution you would like

A clear and concise description of what the desired end result(s) would be.

Describe alternatives you have considered

The README.md should be reorganized so that the flow is, from a high level:

• High Level Overview: What this Demo Does
• Prerequisites
• Let's Run the demo
• Okay, What Did this Demo Just Do?
• Cleaning up

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