Update Sky getting started video (#265)

Author: mellson

docs/stately-sky-getting-started.mdx

@@ -19,7 +19,7 @@ Please note that Sky is currently in beta and will be changing rapidly.
 
 ## Getting started video
 
-<YouTube id="A_J1jbz1oWw" />
+<YouTube id="JJHC0UyGsrQ" />
 
 ## Step 1: Create a machine with Stately