Add recommendation for licensing to Staging Process

[ThisIsMissEm]

Whilst I've recommended the Software and Documents License, there's also additionally licenses for test suites, documents alone and a Intellectual Rights document.

[tantek]

I support the explicit reference to the W3C S&D License. Thanks Emelia.

[ThisIsMissEm]

In the ActivityPub Trust & Safety Taskforce's contributing.md, we have the following:

Contributions to this repository are intended to become part of Recommendation-track documents governed by the W3C Patent Policy and Software and Document License. To make substantive contributions to specifications, you must either participate in the relevant W3C Community or Working Group or make a non-member patent licensing commitment.

Maybe that is better language than that which I have used here?

[evanp]

There's already a section on contributions in the CG Charter. with stronger language:

Specifications created in the Community Group must use the W3C Software and Document License. All other documents produced by the group should use that License where possible.

[evanp]

I also think that at least at Stage 0, contributions don't need to be under the CG's IP rules -- in fact, that's the whole point.

I think we should call out when contributions need to be under the CG's contribution rules, and link to those rules directly, rather than reiterating them.

[ThisIsMissEm]

I think it's worth pointing out ahead of time that if you want something to get to standards track, then that's the license it'd be under