Remove method and endpoint_url from 7.1.1 to reduce confusion

[FragLegs]

We describe the delivery field of the Transmitter configuration twice, once in 7.1.1 and again in 10.3.1. In 7.1.1 we point out that it contains a method and an endpoint_url, but we don't mention the optional authorization_header for push based delivery. It would be less confusing to just reference section 10.3.1 (which 7.1.1 already does) and leave off the detailed description of the delivery field. I'm suggesting that 7.1.1 should look something like this

delivery

REQUIRED. A JSON object containing a set of name/value pairs specifying configuration parameters 
for the SET delivery method. The actual delivery method is identified by the special key "method" with 
the value being a URI as defined in 
[Section 10.3.1](https://openid.github.io/sharedsignals/openid-sharedsignals-framework-1_0.html#delivery-meta). 
Depending on the "method" chosen, other fields are required or optional.

leaving off everything that currently follows

[FragLegs]

Do this as part of #226