README "test" description

[gsnedders]

wpt-metadata/README.md

Line 31 in f8f4488

- `test` is a filename, which is relative to the current directory. If it

As I said on Matrix:

Is test not a path-relative-scheme-less-URL, with a single URL-path-segment?

Imagine, e.g., /html/dom/idlharness.https.html?include=(Document|Window): this should be the test idlharness.https.html?include=(Document|Window) in /html/dom/META.yml, and not a filename.