adds `video` shortcode to publish videos from video.infosec.exchange instance

layouts/shortcodes/video.html

@@ -0,0 +1,7 @@
+{{- $id := .Get "id" | default (.Get 0) -}}
+{{- $class := .Get "class" | default (.Get 1) -}}
+{{- $title := .Get "title" | default "Shared video" }}
+<div {{ with $class }}class="{{ . }}"{{ else }}style="position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden;"{{ end }}>
+  <iframe title="{{ $title }}" width="560" height="315" src="https://video.infosec.exchange/videos/embed/{{ $id }}" frameborder="0" allowfullscreen="" {{ if not $class }}style="position: absolute; top: 0; left: 0; width: 100%; height: 100%; border:0;" {{ end }}sandbox="allow-same-origin allow-scripts allow-popups"></iframe>
+</div>
+