document solving Embedded Experiences goal from charter

I have successfully used use of webmention.io's jf2 output + streams.tmb jf2 input (and subsequent HTML5+mf2 output) to do RSVPs embedding on my event posts (see indieweb.org/event#Tantek and indieweb.org/RSVPs#Tantek for links to examples) which is definitely an Embedded Experience per the description in the Chaarter Goals: https://www.w3.org/2013/socialweb/social-wg-charter.html#goals

jf2 should have a section on "implementation classes" (similar to other specs) with subsections such as "API endpoint" (webmention.io would qualify), and perhaps "Embedding Service" (streams.tmb would qualify) that describe how a standard embedding service can be built by consuming jf2, and producing stylable and presentable HTML+mf2 for providing Embedded Experiences

Start with the JF2 specification and the linked Social Web charter goal, then review the webmention.io JF2 output and streams.tmb JF2 input examples cited in the issue. Done means the specification documents implementation classes, including the proposed API endpoint and embedding service examples, with the Embedded Experience use case explained.

Written by the indexing model from the issue text.