[webpayments] Payment Request Architecture glossary should include IG glossary (#23)

The [Payment Request Architecture glossary](http://wicg.github.io/paymentrequest/specs/architecture.html#glossary) should import the Web Payments IG glossary. I have included all the terms in the PRA glossary in the Web Payments IG glossary and marked them as experimental.

An example of how to do this is in the Web Payments CG's Browser API spec:

https://github.com/WICG/web-payments-browser-api/blob/5034393370c54226eb13fbdacde2462ba5e11713/index.html#L170-L177

You will also need to include a script here:

https://github.com/WICG/web-payments-browser-api/blob/5034393370c54226eb13fbdacde2462ba5e11713/index.html#L13

which can be found here:

https://github.com/WICG/web-payments-browser-api/blob/5034393370c54226eb13fbdacde2462ba5e11713/utils.js

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/webpayments/issues/23