DOC: Small formatting fix for photom arguments

[pllim]

This PR is a follow-up of #10530 towards #9793 and #10529

https://jwst-pipeline--10606.org.readthedocs.build/en/10606/jwst/photom/arguments.html

Tasks

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  • update or add relevant tests
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.59%. Comparing base (2976f24) to head (5901e6a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #10606      +/-   ##
==========================================
- Coverage   86.59%   86.59%   -0.01%     
==========================================
  Files         374      374              
  Lines       40471    40471              
==========================================
- Hits        35047    35045       -2     
- Misses       5424     5426       +2     

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