Motivation
I'm not sure this is possible in Bitbucket but at least it might be possible for the development of usethis itself on Github (and might be used in a future usethis ci github interface.

Only triggering CI when there are actually changes to the codebase that affect CI would potentially stop unnecessary CI runs.

Summary of desired enhancement
A way to avoid triggering CI when doing doc-only changes (e.g. only README).