[ServiceWorker] typo: excecution -> execution (#739)

There's not much to this; I just noticed a typo and thought you might like to merge the fix.
You can view, comment on, or merge this pull request online at:

  https://github.com/slightlyoff/ServiceWorker/pull/739

-- Commit Summary --

  * typo: excecution -> execution

-- File Changes --

    M explainer.md (2)

-- Patch Links --

https://github.com/slightlyoff/ServiceWorker/pull/739.patch
https://github.com/slightlyoff/ServiceWorker/pull/739.diff

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/pull/739