Dropbox connectors: add embed link to replacement how-to video (#445)

Author: Paul-Cornell

snippets/general-shared-text/dropbox.mdx

@@ -1,3 +1,13 @@
+<iframe
+width="560"
+height="315"
+src="https://www.youtube.com/embed/Vku5uYa-2N4"
+title="YouTube video player"
+frameborder="0"
+allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture"
+allowfullscreen
+></iframe>
+
 1. A [Dropbox account](https://www.dropbox.com/try/teams).
 2. A Dropbox app for your Dropbox account. To create a Dropbox app, do the following: