add description in scanner page

[ShengqiWang]

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Comprehensive Summary of your change

Issue being fixed

Fixes #19647

Please indicate you've done the following:

• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (49ee3b7) 67.56% compared to head (2c43697) 67.55%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19733      +/-   ##
==========================================
- Coverage   67.56%   67.55%   -0.01%     
==========================================
  Files         991      991              
  Lines      109167   109167              
  Branches     2719     2719              
==========================================
- Hits        73755    73747       -8     
- Misses      31447    31455       +8     
  Partials     3965     3965              

Flag	Coverage Δ
unittests	67.55% <ø> (-0.01%)	⬇️

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see 3 files with indirect coverage changes

[xuelichao]

UI part looks good to me