Góðan dag TAG！

I'm requesting a TAG review of:

• Name: Subresource prefetching+loading via Signed HTTP Exchange
• Specification URL: https://github.com/WICG/webpackage/issues/347
• Explainer, Requirements Doc, or Example code: Explainer
• Tests: not yet
• Primary contacts: @horo-t

We'd prefer the TAG provide feedback as (please select one):

• open issues in our Github repo for each point of feedback
• open a single issue in our Github repo for the entire review
• leave review feedback as a comment in this issue and @-notify [@kinu @jyasskin @sleevi]