Investigate GitHub Actions labeler misses

[ddbeck]

The GitHub Actions labeling workflow seems to be missing some files. Reported in #7244 (comment).

It might be a misconfiguration or it might be that we're affected by a bug in actions/labeler: actions/labeler#107. This is probably worth testing to figure out which it is, probably on a fork to limit noise on this repo.

[saschanaz]

The glob:

browser-compat-data/.github/labeler.yml

Lines 30 to 31 in 987951e

	docs :writing_hand::
	- "**.md"

Is it a valid syntax? Should it be **/*.md instead?

Edit: #6670 also had the same issue.