JP-3857 Code Style changes for linearity step

[jemorrison]

Helps to resolves JP-3857

This PR updates the linearity step with the new code style for doc strings

Tasks

• If you have a specific reviewer in mind, tag them.
• add a build milestone, i.e. Build 12.0 (use the latest build if not sure)
• Does this PR change user-facing code / API? (if not, label with no-changelog-entry-needed)
  • write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see changelog readme for instructions)
  • update or add relevant tests
  • update relevant docstrings and / or docs/ page
  • start a regression test and include a link to the running job ([click here for instructions]
    https://github.com/spacetelescope/RegressionTests/actions/runs/14342258052
  • (https://github.com/spacetelescope/RegressionTests/blob/main/docs/running_regression_tests.md))
    • Do truth files need to be updated ("okified")?
      • after the reviewer has approved these changes, run okify_regtests to update the truth files
• if a JIRA ticket exists, make sure it is resolved properly

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 3 lines in your changes missing coverage. Please review.

Project coverage is 75.39%. Comparing base (d32c679) to head (ff5d398).
Report is 673 commits behind head on main.

Files with missing lines	Patch %	Lines
jwst/linearity/linearity_step.py	62.50%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9368   +/-   ##
=======================================
  Coverage   75.39%   75.39%           
=======================================
  Files         368      368           
  Lines       36842    36842           
=======================================
  Hits        27777    27777           
  Misses       9065     9065           

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[jemorrison]

@melanieclarke Ready for review. Regression tests have passed.

[melanieclarke]

Looks good! It needs one small typo correction, then we should be able to get this in.

[melanieclarke]

LGTM!