docs: Fix typo in docs/config/README.md

[romainbou]

Description

Motivation and Context

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[mention-bot]

@romainbou, thanks for your PR! By analyzing the history of the files in this pull request, we identified @donatello to be a potential reviewer.

[codecov-io]

Codecov Report

Merging #4009 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #4009      +/-   ##
==========================================
+ Coverage   68.21%   68.26%   +0.05%     
==========================================
  Files         174      174              
  Lines       23738    23738              
==========================================
+ Hits        16193    16205      +12     
+ Misses       6456     6446      -10     
+ Partials     1089     1087       -2

Impacted Files	Coverage Δ
cmd/posix.go	73.4% <0%> (+0.15%)	⬆️
cmd/xl-v1-utils.go	92.18% <0%> (+0.82%)	⬆️
cmd/xl-v1-metadata.go	72.85% <0%> (+0.95%)	⬆️
cmd/fs-v1-background-append.go	79.86% <0%> (+1.34%)	⬆️
cmd/fs-v1-helpers.go	53.87% <0%> (+2.04%)	⬆️

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