update iframe to videoembed (#25783)

Author: im2nguyen

website/content/intro/index.mdx

@@ -10,13 +10,7 @@ description: >-
 
 Welcome to the intro guide to Nomad. This guide is the best place to start with Nomad. We cover what Nomad is, what problems it can solve, how it compares to existing software, and how you can get started using it. If you are familiar with the basics of Nomad, the [documentation](/nomad/docs) and [tutorials](/nomad/tutorials) provide a more detailed reference of available features.
 
-<iframe
-  src="https://www.youtube.com/embed/s_Fm9UtL4YU"
-  frameBorder="0"
-  allowFullScreen={true}
-  width="560"
-  height="315"
-></iframe>
+<VideoEmbed url="https://www.youtube.com/embed/s_Fm9UtL4YU"/>
 
 ## What is Nomad?