feat: Add missing values_editable_by field for organization custom properties

[lrstanley]

Adds missing field values_editable_by for custom properties, as well as mirrors the field documentation directly from the API documentation for the other fields of custom properties.

Ref: https://docs.github.com/en/rest/orgs/custom-properties?apiVersion=2022-11-28#create-or-update-custom-properties-for-an-organization

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.91%. Comparing base (2b8c7fa) to head (2480461).
Report is 57 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3164      +/-   ##
==========================================
- Coverage   97.72%   92.91%   -4.81%     
==========================================
  Files         153      171      +18     
  Lines       13390    11502    -1888     
==========================================
- Hits        13085    10687    -2398     
- Misses        215      724     +509     
- Partials       90       91       +1     

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[gmlewis]

Thank you, @lrstanley !
LGTM.
Merging.