Update frontend/asset_mapper.rst

Co-authored-by: Alexandre Daubois <[email protected]>

Author: damienfern

frontend/asset_mapper.rst

@@ -958,7 +958,7 @@ rendered by the ``{{ importmap() }}`` Twig function:
 ``framework.asset_mapper.config_reader_id``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Sometimes you may want to create your own config reader to load your importmap or use a custom one from a 3rd party package. You can do this by creating a service that implements ``ImportMapConfigReaderInterface`` and then setting the ``config_reader_id`` option:
+Sometimes you may want to create your own config reader to load your importmap or use a custom one from a third party package. You can do this by creating a service that implements ``ImportMapConfigReaderInterface`` and then setting the ``config_reader_id`` option:
 
 .. code-block:: yaml