Add more groups to Volunteering suggestions

[pkkim]

As far as I know, SURJ does good work, but they are an organization explicitly for white people to organize other white people. Let's add some options for everybody to get involved! I'd be happy to help identify local organizations in the USA / coordinate other people doing so. At the very least, I think it should be mentioned that POC can seek out local Black Lives Matter organizations to work with.

[ryanprior]

Thank you for the suggestions, @pkkim. If you can go ahead and identify some good choices, paste the links and contact info for those orgs here along with any notes on which might be most appropriate for whom, and I can help you create a pull request.