Update config.md

[keke1u]

Fixed some typos.

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Motivation

Fixed some typos of the config.md.

Modification

Please briefly describe what modification is made in this PR.

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repos?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects, like MMDet or MMDet3D.
4. The documentation has been modified accordingly, like docstring or example tutorials.

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All committers have signed the CLA.

[codecov]

Codecov Report

Merging #678 (dfd5194) into master (81a4ece) will not change coverage.
The diff coverage is n/a.

❗ Current head dfd5194 differs from pull request most recent head 1fd803f. Consider uploading reports for the commit 1fd803f to get more accurate results

@@           Coverage Diff           @@
##           master     #678   +/-   ##
=======================================
  Coverage   85.18%   85.18%           
=======================================
  Files         105      105           
  Lines        5670     5670           
  Branches      923      923           
=======================================
  Hits         4830     4830           
  Misses        662      662           
  Partials      178      178           

Flag	Coverage Δ
unittests	85.16% <ø> (ø)

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[Junjun2016]

Hi @keke1u
Thanks for your PR！

[OpenMMLab-Coodinator]

Hi @keke1u ！First of all, we want to express our gratitude for your significant PR in this 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.

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Thank you again for your contribution❤