add Config.Explain

[ktong]

No description provided.

[codecov]

Codecov Report

Attention: 9 lines in your changes are missing coverage. Please review.

Comparison is base (6699d06) 73.8% compared to head (0446efd) 74.3%.
Report is 1 commits behind head on main.

❗ Current head 0446efd differs from pull request most recent head 160d054. Consider uploading reports for the commit 160d054 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##            main     #78     +/-   ##
=======================================
+ Coverage   73.8%   74.3%   +0.4%     
=======================================
  Files         17      17             
  Lines        662     709     +47     
=======================================
+ Hits         489     527     +38     
- Misses       155     163      +8     
- Partials      18      19      +1     

Files	Coverage Δ
default.go	76.9% <0.0%> (-6.5%)	⬇️
config.go	89.2% <92.6%> (+0.7%)	⬆️
option.go	25.0% <0.0%> (-8.4%)	⬇️