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

[diverdane]

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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.

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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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