Update text of a non-normative description of respondWith to a note.
Update text of a non-normative description of respondWith to a note.

martinthomson/ServiceWorker,martinthomson/ServiceWorker,chadoliver/ServiceWorker,chadoliver/ServiceWorker,slightlyoff/ServiceWorker,zuzusik/ServiceWorker,slightlyoff/ServiceWorker,mkruisselbrink/ServiceWorker,justinleoye/ServiceWorker,justinleoye/ServiceWorker,mkruisselbrink/ServiceWorker,justinleoye/ServiceWorker,martinthomson/ServiceWorker,zuzusik/ServiceWorker,chadoliver/ServiceWorker,zuzusik/ServiceWorker