2020-04-02 charter updates

[hober]

We published an updated charter today which contains a number of improvements:

• like the proposals repo's README.md already states, the charter now says that Proposals produce explainers, and Work Items produce explainers and specifications;
• spell out what Proposals and Work Items are in terms of the W3C Community and Business Group Process;
• clarify that the purpose of specification is to achieve independent, interoperable implementations;
• clarified that the rules around feature additions and removals are for Work Items, not Proposals;
• and the Chairs are now required to ensure that contributions to Proposals are only made by participants who have agreed to the CLA.

These changes were landed in PRs privacycg/privacycg.github.io#14, privacycg/privacycg.github.io#19, and privacycg/privacycg.github.io#21. You can see the combined diff here.

As with all announcements, we'll talk about this on our next telcon, and will leave this notice up for at least a week.