scene: add play button

public/index.html

@@ -121,7 +121,7 @@
   <section id="scene">
     <div class="container">
       <div class="row">
-        <video src="img/scene.webm" type="video/webm" class="img-fluid force-autoplay" playsinline autoplay loop onclick="this.play()"></video>
+        <video src="img/scene.webm" type="video/webm" class="img-fluid force-autoplay" poster="img/scene-play.png" playsinline autoplay loop onclick="this.play()"></video>
       </div>
     </div>
   </section>