[docs] A reference of the field variable is missing in the sidebar (#6815)

site/content/tutorial/06-bindings/14-component-this/text.md

@@ -2,9 +2,13 @@
 title: Binding to component instances
 ---
 
-Just as you can bind to DOM elements, you can bind to component instances themselves. For example, we can bind the instance of `<InputField>` to a prop named `field` in the same way we did when binding DOM Elements
+Just as you can bind to DOM elements, you can bind to component instances themselves. For example, we can bind the instance of `<InputField>` to a variable named `field` in the same way we did when binding DOM Elements
 
 ```html
+<script>
+	let field;
+</script>
+
 <InputField bind:this={field} />
 ```