added a simple README file

README.rst

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+Symfony Recipes (Contrib)
+=========================
+
+Symfony recipes allow the automation of Composer packages configuration via the
+`Symfony Flex`_ Composer plugin.
+
+This repository hosts contributed recipes for Composer packages that are not
+part of the "official" `Symfony recipes`_. To enable this repository in your
+project, run the following command:
+
+.. code-block:: bash
+
+    composer config extra.symfony.allow-contrib true
+
+For more information about contributing a recipe, read the `documentation`_ on
+the main repository.
+
+.. _`Symfony Flex`: https://github.com/symfony/flex
+.. _`Symfony recipes`: https://github.com/symfony/recipes
+.. _`documentation`: https://github.com/symfony/recipes