Add WPT metadata to spec

[TimvdLippe]

No description provided.

[yoavweiss]

LGTM

[w3cbot]

yoavweiss marked as non substantive for IPR from ash-nazg.

[yoavweiss]

Hmm, this seems to get bikeshed failures:

    $ bikeshed --die-on=warning spec "index.bs" "index.bs.built.html" 
      WARNING: There are 22 WPT tests underneath your path prefix '/reporting/' that aren't in your document and must be added. (Use a <wpt hidden> if you don't actually want them in your document.)
        reporting/bufferSize.html
        reporting/cross-origin-report-no-credentials.https.sub.html
        reporting/cross-origin-reports-isolated.https.sub.html
        reporting/cross-origin-same-site-credentials.https.sub.html
        reporting/disconnect.html
        reporting/document-reporting-bypass-report-to.https.sub.html
        reporting/document-reporting-default-endpoint.https.sub.html
        reporting/document-reporting-destroy-after-document-close.https.sub.html
        reporting/document-reporting-named-endpoints.https.sub.html
        reporting/document-reporting-not-batch-different-document.https.html
        reporting/document-reporting-override-endpoint.https.sub.html
        reporting/document-reporting-path-absolute.https.sub.html
        reporting/generateTestReport-honors-endpoint.https.sub.html
        reporting/generateTestReport.html
        reporting/idlharness.any.js
        reporting/nestedReport.html
        reporting/order.html
        reporting/reporting-api-honors-limits.https.sub.html
        reporting/reporting-isolated-across-navigations.https.sub.html
        reporting/same-origin-cross-site-credentials.https.sub.html
        reporting/same-origin-report-credentials.https.sub.html
        reporting/same-origin-same-site-credentials.https.sub.html
       ✘  Did not generate, due to errors exceeding the allowed error level.
    Command `bikeshed --die-on=warning spec "index.bs" "index.bs.built.html" ` failed with exit code: 2.
    ```

[TimvdLippe]

Apparently ths tests need to be explicitly listed in the documented. I copied that approach from Trusted Types: https://github.com/w3c/trusted-types/blob/279d0ddb1e96173bd3d471306ee22201b07469f3/spec/index.bs#L21