Added variable descriptions to dataclass variables

[j-a-foster]

Description

Missing variable desriptions have been added to variables in superconducting.py data classes.

Replaces #4554 as there were rebasing issues.

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.47619% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 50.05%. Comparing base (add60ca) to head (772fc5e).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
process/models/tfcoil/superconducting.py	90.47%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4591      +/-   ##
==========================================
+ Coverage   49.90%   50.05%   +0.14%     
==========================================
  Files         151      151              
  Lines       29864    29940      +76     
==========================================
+ Hits        14904    14986      +82     
+ Misses      14960    14954       -6     

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[timothy-nunn]

Just a few style comments

[timothy-nunn]

Not a comment for you Jack, I think this class can inherit from CICCAveragedTurnGeometry which will reduce duplication. Will make an issue.

[chris-ashe]

Suggested change

	"""Cable space area (per turn) [m2]
	Includes the area that would be taken up by voids and central cooling channel
	"""Cable space area (per turn), includes the area that would be taken up by voids and central cooling channel [m²]

[j-a-foster]

Had to split between two lines as it was too long, check you're happy with it.