Skip tests for doc-only changes

[robrap]

Devstack provisioning tests require lots of time and energy. Our developers and the earth would be happier if this were skipped on simple doc updates.

Not sure if this helps? https://github.com/microsoft/ebpf-for-windows/pull/1950/files

[nedbat]

A low-tech way to do this is to skip GitHub Action steps based on branch name patterns. The PR author can name the branch to skip the tests when they know it will be ok. I did this in the coverage.py repo here: nedbat/coveragepy@f597744