add docs for $$restProps

site/content/docs/02-template-syntax.md

@@ -113,6 +113,9 @@ An element or component can have multiple spread attributes, interspersed with r
 <Widget {...$$props}/>
 ```
 
+---
+
+*`$$restProps`* references to props that are passed to a component which are not declared with `export`. It is useful for passing down attributes that are not expected as props.
 
 ### Text expressions
 

site/content/tutorial/03-props/04-rest-props/app-a/App.svelte

@@ -0,0 +1,9 @@
+<script>
+	import Input from './Input.svelte';
+
+	export let value = '';
+
+	$: ({ value, ...rest } = $$props);
+</script>
+
+<Input {value} name="email" aria-label="Email" />

site/content/tutorial/03-props/04-rest-props/app-a/Input.svelte

@@ -0,0 +1,7 @@
+<script>
+	export let value = '';
+
+	$: ({ value, ...rest } = $$props);
+</script>
+
+<input bind:value {...rest} />

site/content/tutorial/03-props/04-rest-props/app-b/App.svelte

@@ -0,0 +1,9 @@
+<script>
+	import Input from './Input.svelte';
+
+	export let value = '';
+
+	$: ({ value, ...rest } = $$props);
+</script>
+
+<Input {value} name="email" aria-label="Email" />

site/content/tutorial/03-props/04-rest-props/app-b/Input.svelte

@@ -0,0 +1,5 @@
+<script>
+	export let value = '';
+</script>
+
+<input bind:value {...$$restProps} />

site/content/tutorial/03-props/04-rest-props/text.md

@@ -0,0 +1,9 @@
+---
+title: $$restProps
+---
+
+If you want to pass down props that are not defined with `export`, you can use `$$restProps`:
+
+```html
+<input {...$$restProps}/>
+```