[browser-payment-api] Merge Payment Request Architecture with Capabilities Document (#42)

>From the [Payment Request Architecture](http://wicg.github.io/paymentrequest/specs/architecture.html#abstract) document:

> The Payment Request architecture is designed to separate different concerns of the Payment Request system into different specifications so that they can be discussed and moved forward independently. This document describes the architecture and explains what different specifications may be created and how the relate to each other. [[link](http://wicg.github.io/paymentrequest/specs/architecture.html#abstract)]

It feels like the Payment Request Architecture and the Web Payments IG's Capabilities document overlap (based on the desired goals for the capabilities document). I agree that we need a document like the Payment Request Architecture, but think that it should be placed into the architecture document (capabilities) the WPIG agreed upon.

It's also confusing because it seems like there is also overlap with @adrianhopebailie's architecture document here: https://github.com/w3c/webpayments/wiki/A-Payments-Initiation-Architecture-for-the-Web

Spec refs:
http://wicg.github.io/paymentrequest/specs/architecture.html#abstract

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/browser-payment-api/issues/42