Comment 6 for bug 1903476

I checked this out and it looks good, so it's in master now. I also added a followup commit to limit a rebuild to when a push or PR affects files under docs/ and removed the perl setup action since the ubuntu-latest environment already includes[1] perl 5.30. Thanks Jane!

[1] https://github.com/actions/virtual-environments/blob/main/images/linux/Ubuntu2004-Readme.md