Accessibility additions to iframe (and lazy load)

Author: zachleat

src/site/index.njk

@@ -73,7 +73,7 @@ layout: layouts/base.njk
       <a href="https://www.netlify.com/authors/matt-biilmann/">Matt Biilmann</a> took the concept of Jamstack mainstream with his presentation at Smashing Conf 2016. Watch the quintessential introduction to the Jamstack.
     </p>
     <div class="videowrapper mb-8">
-      <iframe src="https://player.vimeo.com/video/163522126?title=0&byline=0&portrait=0" width="640" height="360" frameborder="0" allow="autoplay; fullscreen" allowfullscreen></iframe>
+      <iframe loading="lazy" src="https://player.vimeo.com/video/163522126?title=0&byline=0&portrait=0" width="640" height="360" frameborder="0" allow="autoplay; fullscreen" allowfullscreen title="Mathias Biilmann Smashing Conf 2016 talk video: The New Front-End Stack"></iframe>
     </div>
     <a href="/learn" class="cta">See more videos and resources</a>
   </div>