Remove extraneous call to loop function (#350)

This extra call to the `loop` function isn't present in `app-b/src/lib/App.svelte`, so it should be removed from the text of the tutorial.

Author: nicholas-wilcox

Diff for: content/tutorial/01-svelte/07-lifecycle/01-onmount/README.md

@@ -49,10 +49,8 @@ onMount(() => {
 		paint(context, t);
 	});
 
-	loop();
-
 +++	return () => {
 		cancelAnimationFrame(frame);
 	};+++
 });
-```
+```