[#587, #607, #608] update config reference and deployment docs

[conceptualshark]

Purpose

Catch the docs up on some missed variable additions/updates from recent work.

Changes

• removed extra text and added in a sample .env file in the deployment guide for easier copy-pasting
• added in the new PORT variable in the config guide and updated sample files
• cleaned up the config guide so it's easier to use

Checklist

• Update CHANGELOG.md file
  • Merge in main so the most recent CHANGELOG.md file is being appended to
  • Add description within the Unreleased section in an appropriate category. Add a new category from the list at the top of the file if the needed one isn't already there.
  • Add a link to this PR at the end of the description with the PR number as the text. example: #1
• Applicable documentation updated (guides, quickstart, postman collections, tutorial, fidesdemo, database diagram.

Ticket

Fixes #587, #608, #607