Feature/oaf 83 refactor envvar docs

[stevenbal]

Closes maykinmedia/open-api-framework#83 partially

Changes

[Describe the changes here]

Checklist

Check off the items that are completed or not relevant.

• Experimental features/changes

  • Any experimental features added in this PR are backwards compatible
  • Any experimental features added in this PR are documented in the docs/api/experimental.rst page

• Commit hygiene

  • Commit messages refer to the relevant Github issue
  • Commit messages explain the "why" of change, not the how

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.72%. Comparing base (8ea34fa) to head (ed8ebd4).
⚠️ Report is 154 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #324   +/-   ##
=======================================
  Coverage   91.72%   91.72%           
=======================================
  Files         109      109           
  Lines        3069     3069           
  Branches      467      467           
=======================================
  Hits         2815     2815           
  Misses        211      211           
  Partials       43       43           

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