Document recent security capabilities of package repositories, and their funding source

[steiza]

This will help package repositories see what each other are working on, link to context to inform future implementations, and document funding sources so interested package repositories can seek our support.

[steiza]

We have an early draft of this at Recent Package Repository Security Capabilities

[steiza]

See also https://github.com/psf/project-funding-wg/blob/master/funders.md