docs: fix note about $derived

Author: Conduitry

documentation/docs/02-runes/03-$derived.md

@@ -21,7 +21,7 @@ The expression inside `$derived(...)` should be free of side-effects. Svelte wil
 
 As with `$state`, you can mark class fields as `$derived`.
 
-> [!NOTE] Code in Svelte components is only executed once at creation, without the `$derived` rune `double` would maintain it's original value.
+> [!NOTE] Code in Svelte components is only executed once at creation. Without the `$derived` rune, `doubled` would maintain its original value even when `count` changes.
 
 ## `$derived.by`