docs: update readme to separate enabling plugin from other dev steps

[saraburns1]

Reorganize development setup instructions and add metrics enabling steps.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.25%. Comparing base (b754b5d) to head (726f55b).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #123   +/-   ##
=======================================
  Coverage   53.25%   53.25%           
=======================================
  Files          15       15           
  Lines         338      338           
  Branches       62       67    +5     
=======================================
  Hits          180      180           
+ Misses        157      149    -8     
- Partials        1        9    +8     

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[bmtcril]

Nice!