Don't use shorthand binding in textarea example (#3256)

site/content/examples/05-bindings/04-textarea-inputs/App.svelte

@@ -1,12 +1,12 @@
 <script>
 	import marked from 'marked';
-	let value = `Some words are *italic*, some are **bold**`;
+	let text = `Some words are *italic*, some are **bold**`;
 </script>
 
 <style>
 	textarea { width: 100%; height: 200px; }
 </style>
 
-<textarea bind:value></textarea>
+<textarea bind:value={text}></textarea>
 
-{@html marked(value)}
+{@html marked(text)}