Clarify docs headers

[braingram]

Updates schema docs to:

• remove mention of "File schemas"
• add a one sentence description
• add links to asdf schema docs and roman_datamodels docs

Link to updated docs: https://rad--446.org.readthedocs.build/en/446/schemas.html

Only a docs change so no downstream tests will be run.

Closes #427

Tasks

• Update or add relevant rad tests.
• Update relevant docstrings and / or docs/ page.
• Does this PR change any schema files?
  • Schema changes were discussed at RAD Review Board meeting.
• 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>").
  • Update relevant roman_datamodels utilities and tests.

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

[braingram]

@PaulHuwe I don't appear to have permissions to request reviewers. Would you take a look?

Also @ketozhang how does the updated wording look to you?

[PaulHuwe]

LGTM with one suggestion

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.45%. Comparing base (c1811ab) to head (f6c4abc).
Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #446      +/-   ##
==========================================
+ Coverage   95.38%   95.45%   +0.06%     
==========================================
  Files           4        4              
  Lines         195      198       +3     
==========================================
+ Hits          186      189       +3     
  Misses          9        9              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[ketozhang]

Looks better, thank you @braingram

Couple of 'file schema' left in the sidebar. If these are truly schemas for the entire file, then this makes sense.

Looks like something is wrong with the TOC

[braingram]

Thanks for taking a look.

#447 addresses the TOC

As the Reference File Schemas are schemas used in reference files I think we have to live with that title. I made a slight change to the page to try and remove some of the ambiguity.

I updated the Ground Tests File Schemas to Ground Tests Schemas.

The issue will remain searchable after it's closed which can also be helpful if someone else runs into this confusion.