add video demo to readme (#438)

Author: tjex

README.md

@@ -4,12 +4,16 @@
 <img alt="Screencast" width="95%" src="docs/assets/media/screencast.svg"/>
 </div>
 
+## Description
+
+`zk` is a command-line tool helping you to maintain a plain text [Zettelkasten](https://zettelkasten.de/introduction/) or [personal wiki](https://en.wikipedia.org/wiki/Personal_wiki).
+
 Looking for a quick usage example? [Let's get started](docs/getting-started.md).
 
+Or want to see it in action? Checkout [Shivan's](https://github.com/shivan-s)
+video, [_Note-taking System ALL Programmers Should Consider_](https://www.youtube.com/watch?v=UzhZb7e4l4Y).
 
-## Description
 
-`zk` is a command-line tool helping you to maintain a plain text [Zettelkasten](https://zettelkasten.de/introduction/) or [personal wiki](https://en.wikipedia.org/wiki/Personal_wiki).
 
 ### Highlights