Minor: Add reference to spec raw format to readme

[Firehed]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.37%. Comparing base (ff3077c) to head (52d40c3).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main      #97   +/-   ##
=========================================
  Coverage     81.37%   81.37%           
  Complexity      335      335           
=========================================
  Files            33       33           
  Lines           988      988           
=========================================
  Hits            804      804           
  Misses          184      184           

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