[Docs] Update README in configs according to OpenMMLab standard.

[mzr1996]

Modification

As the title

Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects, like MMDet or MMSeg.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Merging #672 (70f858e) into dev (a451d63) will not change coverage.
The diff coverage is n/a.

❗ Current head 70f858e differs from pull request most recent head 935d63d. Consider uploading reports for the commit 935d63d to get more accurate results

@@           Coverage Diff           @@
##              dev     #672   +/-   ##
=======================================
  Coverage   82.27%   82.27%           
=======================================
  Files         120      120           
  Lines        7045     7045           
  Branches     1228     1228           
=======================================
  Hits         5796     5796           
  Misses       1075     1075           
  Partials      174      174           

Flag	Coverage Δ
unittests	82.27% <ø> (ø)

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[Ezra-Yu]

LGTM.