Adding supported Node Version for Harbor

[bupd]

Summary

• Updates README to clarify the steps to setup Harbor UI.
• Specifies correct Node.js version to run Harbor UI.

Changes made

• added .nvmrc (to indicate node version)
• updated docs to be clear for newcomers.

Issue being fixed

Fixes #21044

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 ✅

Project coverage is 46.25%. Comparing base (c8c11b4) to head (dbc1e01).
Report is 338 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #21153      +/-   ##
==========================================
+ Coverage   45.36%   46.25%   +0.88%     
==========================================
  Files         244      247       +3     
  Lines       13333    13863     +530     
  Branches     2719     2867     +148     
==========================================
+ Hits         6049     6412     +363     
- Misses       6983     7113     +130     
- Partials      301      338      +37     

Flag	Coverage Δ
unittests	46.25% <ø> (+0.88%)	⬆️

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

see 491 files with indirect coverage changes

[MinerYang]

Please refer to #21044 (comment)

[bupd]

@MinerYang update .nvmrc to the supported version.

[bupd]

Ready for review and merge.!!