Details on rss cloud calls for protocol http-post

Start with the RSS cloud example in the issue and inspect the referenced daverss.js file, especially the existing notification call. Document incoming subscription and outgoing notification examples with the HTTP method, URL, headers, bodies, and status; done means both http-post flows are clearly described.

Hi there - I'd like to support the cloud element over http-post.

Given an rss feed like: https://rss.firesky.tv/?filter=quake

<rss version="2.0" xmlns:source="http://source.scripting.com/">
  <channel>
    ...
    <cloud domain="rss.firesky.tv" port="443" path="/rss-cloud-notify" registerProcedure="" protocol="http-post" />

I'll just be using the web standard fetch api on the server side.

It would help to see:

• an example HTTP request/response incoming subscription call from clients
• an example HTTP request/response outgoing notification call to notify clients (guessing something like this?)

HTTP method/url/headers/bodies/status should be enough.

Thanks!
- John