Implement not found page (#64)

Signed-off-by: Dae❤️ <74119677+daeisbae@users.noreply.github.com>

Author: daeisbae

src/app/[ownerSlug]/[repoSlug]/not-found.tsx

@@ -0,0 +1,11 @@
+import { JSX } from 'react'
+import React from 'react'
+
+export default function NotFound() {
+
+    return (
+        <div>
+            <h1>The repository is not created yet</h1>
+        </div>
+    )
+}

src/app/not-found.tsx

@@ -0,0 +1,9 @@
+export default function NotFound() {
+    return (
+        <div>
+            <h1>
+                404 - Page Not Found
+            </h1>
+        </div>
+    )
+}