feat(article): add video shortcode (#280)

assets/scss/partials/layout/article.scss

@@ -385,7 +385,7 @@
         padding-bottom: 56.25%;
         overflow: hidden;
 
-        & > iframe {
+        & > iframe, & > video {
             position: absolute;
             width: 100%;
             height: 100%;

layouts/shortcodes/video.html

@@ -0,0 +1,13 @@
+<div class="video-wrapper">
+    <video
+    controls
+    {{ with .Get "poster" }}poster="{{- . -}}"{{ end }}
+    {{ with .Get "src" }}src="{{- . -}}"{{ end }}
+    {{ with .Get "autoplay" }}autoplay{{ end }}
+    >
+        <p>
+            Your browser doesn't support HTML5 video. Here is a
+            <a href="{{ with .Get "src" }}{{- . -}}{{ end }}">link to the video</a> instead.
+        </p>
+    </video>
+</div>