Added comment about improving accessibilty of images.

ResponsiveImages.html

@@ -213,7 +213,7 @@ <h1>Goals</h1>
     <ul>
           <li>Will degrade gracefully on older user agents.</li>
           <li>Can be polyfilled.</li>
-          <li>Retains, at a minimum, the same level of accessibility as current <code>img</code> element.</li>
+          <li>Retains, at a minimum, the same level of accessibility as current <code>img</code> element - and we may even be able to do better! </li>
           <li>Adhere to common conventions around for content, markup, behavior, and styling.</li>
           <li>Provides a purely client-side solution that can rely on scripts, but doesn&rsquo;t require it. Similarly, this solution must not require the use of any server-side technologies to reliably deliver content tailored for the end user&rsquo;s browsing situation.</li>
           <li>Supports use cases where authors need to explicitly define different image versions as opposed to simply different resolutions of the same image.</li>