docs(README): improve logger description

[L2ncE]

What type of PR is this?

docs

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• This PR title match the format: <type>(optional scope): <description>
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优化对 README 中 logger 的描述

Which issue(s) this PR fixes:

None.

[codecov]

Codecov Report

Base: 66.53% // Head: 66.54% // Increases project coverage by +0.01% 🎉

Coverage data is based on head (5054dab) compared to base (3f8c34e).
Patch has no changes to coverable lines.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #362      +/-   ##
===========================================
+ Coverage    66.53%   66.54%   +0.01%     
===========================================
  Files           89       89              
  Lines         8495     8507      +12     
===========================================
+ Hits          5652     5661       +9     
- Misses        2482     2484       +2     
- Partials       361      362       +1     

Impacted Files	Coverage Δ
pkg/common/timer/timer.go	61.90% <0.00%> (-19.05%)	⬇️
pkg/app/server/option.go	96.63% <0.00%> (ø)
pkg/common/config/option.go	100.00% <0.00%> (ø)
pkg/route/engine.go	62.63% <0.00%> (+0.57%)	⬆️
pkg/common/compress/compress.go	83.80% <0.00%> (+2.85%)	⬆️

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