[push-api] Move to using just endpoint (#129)

There was a lot of text here that was simply wrong, probably because it was outdated.

I've removed or reworked that part.  I haven't cited the IETF work (yet), but there is a placeholder there.

Closes #56.
You can view, comment on, or merge this pull request online at:

  https://github.com/w3c/push-api/pull/129

-- Commit Summary --

  * Starting to remove subscription id
  * Tweak example
  * Removing subscriptionId

-- File Changes --

    M index.html (104)

-- Patch Links --

https://github.com/w3c/push-api/pull/129.patch
https://github.com/w3c/push-api/pull/129.diff

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/push-api/pull/129