fix: correct path for 404 error page in default configuration

config/default.conf

@@ -13,6 +13,7 @@ server {
     index index.html index.htm;
 
     error_page 400 /400.html;
+    error_page 404 ./error_pages/404.html;
     error_page 403 /403.html;
     error_page 404 /404.html;
     error_page 405 /405.html;