fix(dev): correct AuthorMapper registration example (return new AuthorMapper)

Agent-Logs-Url: https://github.com/nextcloud/documentation/sessions/1c4f547a-dfc0-437f-8427-722e03179f75

Co-authored-by: skjnldsv <14975046+skjnldsv@users.noreply.github.com>

Author: Copilot

developer_manual/basics/dependency_injection.rst

@@ -280,7 +280,7 @@ The container works in the following way:
 * **AuthorMapper** is queried::
 
     $container->registerService(AuthorMapper::class, function(ContainerInterface $c): AuthorMapper {
-      return new AuthorService(
+      return new AuthorMapper(
         $c->get(IDBConnection::class)
       );
     });