load html on compile time instead of runtime.

Maybe fixed not found link to refer to correct url in release

src/resources/static/not-found.html

@@ -54,7 +54,7 @@
 <div class="container">
     <h1>404</h1>
     <p>Oops! Page not found.</p>
-    <a href="http://localhost:8000/openapi">Go back to the documentation</a>
+    <a href="{{docs}}">Go back to the documentation</a>
 </div>
 </body>
 </html>