Add example models required for ccsp docs

[braingram]

Companion PR to spacetelescope/rad#747

Add example CCSP models.

Tasks

• Update or add relevant roman_datamodels tests.
• Update relevant docstrings and / or docs/ page.
• Does this PR change any API used downstream? (If not, label with no-changelog-entry-needed.)
  • Write news fragment(s) in changes/: echo "changed something" > changes/<PR#>.<changetype>.rst (see below for change types).
  • Start a romancal regression test (https://github.com/spacetelescope/RegressionTests/actions/workflows/romancal.yml) with this branch installed ("git+https://github.com/<fork>/rad@<branch>").

News fragment change types:

• changes/<PR#>.feature.rst: new feature
• changes/<PR#>.bugfix.rst: fixes an issue
• changes/<PR#>.doc.rst: documentation change
• changes/<PR#>.removal.rst: deprecation or removal of public API
• changes/<PR#>.misc.rst: infrastructure or miscellaneous change

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.84%. Comparing base (087a60d) to head (727107c).
⚠️ Report is 207 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #597      +/-   ##
==========================================
- Coverage   97.56%   94.84%   -2.72%     
==========================================
  Files          30       26       -4     
  Lines        2788     2619     -169     
==========================================
- Hits         2720     2484     -236     
- Misses         68      135      +67     

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[PaulHuwe]

LGTM. Remember to update the RAD pointing.