Make docs for provider module consistent

[sffc]

See #681

This adds basic docs for the provider modules in each component.

[codecov-commenter]

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.18%. Comparing base (6030ec1) to head (df785d8).
⚠️ Report is 3824 commits behind head on main.
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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #683      +/-   ##
==========================================
- Coverage   74.24%   74.18%   -0.06%     
==========================================
  Files         171      171              
  Lines       10824    10802      -22     
==========================================
- Hits         8036     8014      -22     
  Misses       2788     2788              

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[coveralls]

Pull Request Test Coverage Report for Build a51ba8be6d73e67c4118e51ab60af95b32bea399-PR-683

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.009%) to 73.439%

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Files with Coverage Reduction	New Missed Lines	%
experimental/provider_ppucd/src/parse_ppucd.rs	1	93.0%

Totals
Change from base Build 9015f7820c614afd288567efb2cd80b1eccd2a2e:	-0.009%
Covered Lines:	8140
Relevant Lines:	11084

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