docs: Extend the description of ref parameters

[alexandear]

ref descriptions are copied from the appropriate pages in GitHub documentation.

Updates #3630

[gmlewis]

Thank you, @alexandear!
LGTM.
Merging.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.

Project coverage is 91.32%. Comparing base (74b2ca0) to head (9209c58).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
example/commitpr/main.go	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3643      +/-   ##
==========================================
- Coverage   91.33%   91.32%   -0.02%     
==========================================
  Files         184      184              
  Lines       16174    16176       +2     
==========================================
  Hits        14773    14773              
- Misses       1227     1229       +2     
  Partials      174      174              

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.