Added upload video

website/src/docs/hotchocolate/server/files.md

@@ -25,6 +25,10 @@ This however has a couple of downsides:
 
 Hot Chocolate implements the [GraphQL multipart request specification](https://github.com/jaydenseric/graphql-multipart-request-spec) which adds a new `Upload` scalar and allows our GraphQL server to handle file upload streams.
 
+<iframe width="560" height="315"
+src="https://www.youtube.com/embed/XeF3IuGDq4A"frameborder="0"
+allowfullscreen></iframe>
+
 > ⚠️ Note: Files can not yet be uploaded through a gateway to stitched services using the `Upload` scalar.
 
 ### Usage