Workaround for required checks blocking *.md PR merges

[rcowsill]

This repo has been configured to require the build workflow to pass for any PR before it can be merged. The build workflow ignores changes that only modify .md files:

runner/.github/workflows/build.yml

Lines 14 to 15 in b6dbf42

	paths-ignore:
	- '**.md'

Skipped workflows are treated as "not succeeded", which means PRs that only update documentation are blocked from merging:

https://github.community/t/unable-to-merge-pull-request-due-to-branch-protection-rules-since-github-actions-check-doesnt-trigger/126250

That also applies to auto-merge; it can be activated, but will never happen due to the pending "required" checks (eg #1379)

Hopefully the "required checks" system will be improved to handle this case, but in the meantime perhaps it's worth investigating one of the workarounds from this thread:

https://github.community/t/feature-request-conditional-required-checks/16761

That way the workflow would always succeed for docs-only PRs due to the build steps/jobs being skipped.