[Tutorial] Update Chapter 19 to reference Svelte Kit

Maybe this is intentional and the Svelte team prefers to wait until the v1.0.0 version is released, I'm just opening this PR to keep track of this as I haven't found any existing issue or PR mentioning it.

site/content/tutorial/19-next-steps/01-congratulations/text.md

@@ -6,6 +6,6 @@ You've now finished the Svelte tutorial and are ready to start building apps. Yo
 
 To get set up in your local development environment, check out [the quickstart guide](blog/the-easiest-way-to-get-started).
 
-If you're looking for a more expansive framework that includes routing, server-side rendering and everything else, take a look at [Sapper](https://sapper.svelte.dev).
+If you're looking for a more expansive framework that includes routing, server-side rendering and everything else, take a look at [Svelte Kit](https://kit.svelte.dev).
 
 Most importantly: since you're now a member of the Svelte community, you should [join our friendly Discord chatroom](chat). That's where you'll find fellow Svelte users, and it's where we plan the future of the framework.