Designate points-of-contact: test reviewers

[jugglinmike]

Find a handful of conformance test writers who would like to be available for new contributors. Ensure that they're comfortable having their contact information published in this guide.

[boazsender]

@jugglinmike suggested referencing WPT's "META>yml" files instead. I'm open to it, but I think we need consent from those reviewers to be in the book, or a notice in the repo that says we pull from there.