update the readme to generate a datamap

[conceptualshark]

Closes #431, #680

Code Changes

• Issue Update README Quickstart to suggest a pip install #431 was originally created to swap the readme's quickstart to pip install, but after discussion, we opted to refactor the quick start into a demo of the data mapping/ropa generation instead.
• The readme now walks a user through using the demo resources to generate a basic data map, and then directs to the existing documentation to expand that for a fully-compliant RoPA.
• Also snuck in a quick update to the install guide to update the wording for Update "Running Fidesctl in Docker" guide to include a version tag #680

Pre-Merge Checklist

• All CI Pipelines Succeeded
• Documentation Updated:
  • documentation complete, or draft/outline provided (tag docs-team to complete/review on this branch)
• Issue Requirements are Met
• [] Update CHANGELOG.md

[ThomasLaPiana]

LGTM! Nice README update. Going to go ahead and merge this now so I can work on another ticket related to updating the README