[fix] no ssr for Svelte tutorials (sveltejs#107)

Fixes sveltejs#106

Author: dummdidumm

content/tutorial/01-svelte/common/src/routes/+layout.js

@@ -0,0 +1 @@
+export const ssr = false;

content/tutorial/03-advanced-svelte/common/src/routes/+layout.js

@@ -0,0 +1 @@
+export const ssr = false;