[Openid-specs-fapi] New document to adopt: HTTP Signature Requirements

[Nat Sakimura]

Dear FAPIers:

As noted in the meeting minutes of July 17[1], two documents are asked 
to be adopted by the WG>
This document is the second of those.

* `HTTP Signing Doc 
https://bitbucket.org/josephheenan/fapi/src/http-signing/Financial_API_HTTP_Signing.md

In the call, the WG agreed to first concentrate on the Requirements and 
Use-cases.
If we want later, we can expand the scope of the document or create a 
new one (possibly at other fora as well.)

If you have objections, please speak up within a week.
If not, the document will be adopted.

Best,

Nat Sakimura

[1] 
https://bitbucket.org/openid/fapi/wiki/FAPI_Meeting_Notes_2019-07-17_Atlantic