[Docs] Add the top-5 acc in ResNet-CIFAR README.

[huoshuai-dot]

add the top-5 acc on CIFAR-10.

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #531 (6713cc5) into master (e0d32df) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #531   +/-   ##
=======================================
  Coverage   79.65%   79.65%           
=======================================
  Files         106      106           
  Lines        6006     6006           
  Branches      973      973           
=======================================
  Hits         4784     4784           
  Misses       1092     1092           
  Partials      130      130           

Flag	Coverage Δ
unittests	79.65% <ø> (ø)

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[Ezra-Yu]

Please sign the CLA before we can accept your contribution.

[huoshuai-dot]

Please sign the CLA before we can accept your contribution.

ok!

[mzr1996]

Thanks for supplement

[OpenMMLab-Assistant005]

Hi @huoshuai-dot ！First of all, we want to express our gratitude for your significant PR in the MMCls project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

We would also like to invite you to join our Special Interest Group (SIG) private channel on Discord, where you can share your experiences, ideas, and build connections with like-minded peers. To join the SIG channel, simply message moderator— OpenMMLab on Discord or briefly share your open-source contributions in the #introductions channel and we will assist you. Look forward to seeing you there! Join us ：https://discord.gg/UjgXkPWNqA

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