Make sure mailing list info is provided WGs

[marcoscaceres]

Important info

• URL to affected spec: https://w3c.github.io/mathml-core/

Description of problem

What happened (e.g., it crashed)?:

We would accept comments either as github issues at w3c/mathml-core or on the mailing list www-math@w3.org I have

      wgPublicList: "www-math",
      github: "w3c/mathml-core",

in respecConfig but the mailing list isn't added. The github issues link is added but pubrules moans

No mailing list link.
It must include a public archived place to send comments to in the headers (

) of the document. (GitHub repository issue links are expected to be of the form https://github.com/<USER_OR_ORG>/<REPO_NAME>/[issues|labels][/…].)

[marcoscaceres]

Closing in favor of w3c/specberus#1309