Remove docs Layout console warnings

Author: techniq

src/docs/Layout.svelte

@@ -14,10 +14,10 @@
 
 <script>
   // frontmatter: https://mdsvex.com/docs#frontmatter-1
-  export let name;
-  export let sourceUrl;
-  export let docUrl;
-  export let description;
+  export let name = undefined;
+  export let sourceUrl = undefined;
+  export let docUrl = undefined;
+  export let description = undefined;
 </script>
 
 {#if name}