fix(material-angular-io): update site images

The site images, e.g. when linking the docs site on social media, were still using the M2 appearance. These changes update the images and delete some unnecessary ones.

Author: crisbeto

material.angular.io/scenes/src/app/scene-viewer/scene-viewer.scss

@@ -13,4 +13,5 @@ app-scene-viewer {
   top: 0;
   height: 100%;
   width: 100%;
+  pointer-events: none;
 }