*: add some comments to exported function, part of enable revive.exported

[okJiang]

What problem does this PR solve?

Issue Number: Ref #8458, #8440 (comment)

What is changed and how does it work?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has the configuration change
• Has HTTP API interfaces changed (Don't forget to add the declarative for the new API)
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• PR to update pingcap/tiup:
• Need to cherry-pick to the release branch

Release note

None.

[ti-chi-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[codecov]

Codecov Report

Attention: Patch coverage is 90.80460% with 8 lines in your changes missing coverage. Please review.

Project coverage is 77.46%. Comparing base (9af28fc) to head (da29bf9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8459      +/-   ##
==========================================
- Coverage   77.48%   77.46%   -0.03%     
==========================================
  Files         472      472              
  Lines       61798    61796       -2     
==========================================
- Hits        47887    47868      -19     
- Misses      10341    10360      +19     
+ Partials     3570     3568       -2     

Flag	Coverage Δ
unittests	77.46% <90.80%> (-0.03%)	⬇️

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: HuSharp, rleungx

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• OWNERS [HuSharp,rleungx]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-31 02:53:38.786772146 +0000 UTC m=+324335.066820213: ☑️ agreed by HuSharp.
• 2024-07-31 06:33:05.967753119 +0000 UTC m=+337502.247801188: ☑️ agreed by rleungx.

[ti-chi-bot]

@okJiang: Your PR was out of date, I have automatically updated it for you.

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