[push-api] Rewording abstract text again (#152)

I had some time on the train; I'm not sure that this is better, but I didn't like the use of "server-sent events"
You can view, comment on, or merge this pull request online at:

  https://github.com/w3c/push-api/pull/152

-- Commit Summary --

  * Rewording abstract text again

-- File Changes --

    M index.html (14)

-- Patch Links --

https://github.com/w3c/push-api/pull/152.patch
https://github.com/w3c/push-api/pull/152.diff

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Reply to this email directly or view it on GitHub:
https://github.com/w3c/push-api/pull/152