Clarify behavior around field defaults in the docs

[swrichards]

No description provided.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.65%. Comparing base (0c55577) to head (1aa987b).
Report is 26 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #22      +/-   ##
==========================================
+ Coverage   96.89%   97.65%   +0.75%     
==========================================
  Files           8       20      +12     
  Lines         193      766     +573     
==========================================
+ Hits          187      748     +561     
- Misses          6       18      +12     

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[swrichards]

@Coperh @SonnyBA tagging you on the documentation PRs given that you've used or are using the API right now, so your sense of whether the docs matched your experience is helpful.

[Coperh]

Looks good