Improve Working Group page

[DanielOaks]

I think there's quite a bit we could do to extend this page and make it more useful for people who are a part of or explicitly interested in joining the working group.

Improving the participation page to include the technical board details in the charter would probably be a part of this (adapting it to use a _data list instead of being defined just on that page so we can add it there too, as well as just improving the look of the thing).

As well as that ircv3 announcements mailing list idea that was suggested, the roadmap stuff that's being done in ircv3/ircv3-specifications#241 and other details we could add or link to this WG page for interested people.

[DanielOaks]

Solved by #115