docs: add code coverage badge back

[linrongbin16]

Regression Test

Platforms

• windows
• macOS
• linux

Hosts

• Test on github.com.
• Test on gitlab.com.
• Test on bitbucket.org.
• Test on codeberg.org.
• Test on git.samba.org.

Functions

• Use GitLink(!) to copy git link (or open in browser).
• Use GitLink(!) blame to copy the /blame link (or open in browser).
• Use GitLink(!) default_branch to open the /main//master link in browser (or open in browser).
• Use GitLink(!) current_branch to open the current branch link in browser (or open in browser).
• Copy git link in a symlink directory of git repo.
• Copy git link in an un-pushed git branch, and receive an expected error.
• Copy git link in a pushed git branch but edited file, and receive a warning says the git link could be wrong.
• Copy git link with 'file' and 'rev' parameters.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.68%. Comparing base (9232f86) to head (ba0824d).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #255      +/-   ##
==========================================
+ Coverage   70.40%   72.68%   +2.28%     
==========================================
  Files          10       10              
  Lines         963      963              
==========================================
+ Hits          678      700      +22     
+ Misses        285      263      -22     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

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