XEP-0455: remove pubsub mention, add accessibility considerations

thanks daniel for pointing out I missed some sentences when cleaning it
up.

Author: mathieui

xep-0455.xml

@@ -68,7 +68,6 @@
         <li>An informational way of exposing an external service endpoint containing machine-readable data using &xep0128;</li>
         <li>A specification of the data this service should provide</li>
         <li>A normative way of providing such information in-band, when the outage is not complete</li>
-        <li>A way to reference and archive such incidents, in a &xep0060; node</li>
     </ul>
 </section1>
 <section1 topic='External status' anchor='external-status'>
@@ -191,14 +190,16 @@
   <p>A client implementing this extension MUST fetch the addresses of the external service and cache it
     for later use. Doing so allows the client to use this information when it is impossible to connect
     to the server.</p>
-  <p>A client receiving an outage event for a time in the future SHOULD treat it as a planned event
+  <p>A client fetching an outage event for a time in the future SHOULD treat it as a planned event
      that is not already happening and adapt its display consequently.</p>
 </section1>
 <section1 topic='Internationalization Considerations' anchor='i18n'>
   <p>Both the JSON and the XML format defined in this document allow for internationalization in the fields that are expected to be presented to the user as-is. The other fields are machine-readable and their various values SHOULD be translated in the implementing applications.</p>
 </section1>
+<section1 topic='Accessibility Considerations' anchor='access'>
+  <p>Clients MUST display the message in a way that makes it as readable as the rest of the application for visually impaired people, and the message text MUST likewise be available to screen readers.</p>
+</section1>
 <section1 topic='Security Considerations' anchor='security'>
-  <p>Client implementations MUST check the provenance of the pubsub notifications before displaying a notification, otherwise malicious entities could send fake outage events.</p>
   <p>Server administrators MUST ensure the servers provided in 'external-status-addresses' are trusted, as malicious administrators of this server could use the referenced file
      to display arbitrary messages to users.</p>
 </section1>