Random doc updates

[gewarren]

Follow up to dotnet/ml-api-docs#175 and other grammar improvements.

So we can do the best job, please check:

• There's a descriptive title that will make sense to other developers some time from now.
• There's associated issues. All PR's should have issue(s) associated - unless a trivial self-evident change such as fixing a typo. You can use the format Fixes #nnnn in your description to cause GitHub to automatically close the issue(s) when your PR is merged.
• Your change description explains what the change does, why you chose your approach, and anything else that reviewers should know.
• You have included any necessary tests in the same PR.

[Copilot]

Pull Request Overview

This PR refines XML documentation across several text and transformer components, improving grammar, clarity, and example references.

• Standardizes summary and <param> XML tags to use action verbs (e.g., “Creates”, “Gets or sets”).
• Improves phrasing and adds <remarks> and explicit <see> links for usage examples.
• Corrects hyphenation and list punctuation in descriptions.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/Microsoft.ML.Transforms.Text/TextFeaturizingEstimator.cs	Refined XML comments: grammar fixes, added <remarks> and <see> links
src/Microsoft.ML.Transforms/CustomMappingTransformer.cs	Enhanced <param> descriptions for better clarity
src/Microsoft.ML.Transforms/CategoricalCatalog.cs	Standardized summary XML to use action verbs

Comments suppressed due to low confidence (1)

src/Microsoft.ML.Transforms.Text/TextFeaturizingEstimator.cs:213

• Since Norm is a public field that can be assigned, consider updating the summary to "Gets or sets the norm of the output vector. It will be normalized to one." to accurately reflect its mutability.

Gets the norm of the output vector. It will be normalized to one.

[ericstj]

Small nit

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.99%. Comparing base (aea5651) to head (fed233f).
Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7476   +/-   ##
=======================================
  Coverage   68.99%   68.99%           
=======================================
  Files        1482     1482           
  Lines      273880   273880           
  Branches    28254    28254           
=======================================
+ Hits       188956   188975   +19     
+ Misses      77540    77522   -18     
+ Partials     7384     7383    -1     

Flag	Coverage Δ
Debug	68.99% <ø> (+<0.01%)	⬆️
production	63.29% <ø> (+<0.01%)	⬆️
test	89.45% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/Microsoft.ML.Transforms/CategoricalCatalog.cs	100.00% <ø> (ø)
...oft.ML.Transforms/Text/TextFeaturizingEstimator.cs	90.32% <ø> (ø)

... and 5 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[gewarren]

@ericstj Can you merge it when you get a chance?