improve Docker wording

Author: dunglas

mercure.rst

@@ -63,24 +63,10 @@ is automatically configured to use it.
 You can jump directly to the next section.
 
 If you use the :doc:`Symfony Local Web Server </setup/symfony_server>`,
-the easiest way to install a Mercure hub is to leverage its :ref:`Docker integration <symfony-server-docker>.
+a Mercure hub will be automatically available as a Docker service thanks to its :ref:`Docker integration <symfony-server-docker>.
 
-First, be sure that recent versions of Docker and Docker Compose are properly installed on your computer.
-Then, create ``docker-compose.yml`` and ``docker-compose.override.yml`` files in your project root directory
-if they don't already exists:
-
-.. code-block:: terminal
-
-    $ echo 'version: "3.8"' > docker-compose.yml
-    $ echo 'version: "3.8"' > docker-compose.override.yml
-
-Then, enable the Docker support of Symfony Flex:
-
-.. code-block:: terminal
-
-    $ composer config --json extra.symfony.docker 'true'
-
-Finally, be sure to start the Symfony Local Web Server with the ``--no-tls`` option:
+Be sure that recent versions of Docker and Docker Compose are properly installed on your computer
+and to start the Symfony Local Web Server with the ``--no-tls`` option:
 
 .. code-block:: terminal
 
@@ -89,15 +75,14 @@ Finally, be sure to start the Symfony Local Web Server with the ``--no-tls`` opt
 Installing the Symfony Bundle
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-In applications using :ref:`Symfony Flex <symfony-flex>`, run this command to
-install the Mercure support before using it:
+Run this command to install the Mercure support before using it:
 
 .. code-block:: terminal
 
     $ composer require mercure
 
-If you previously enabled the Docker support of Symfony Flex, your Docker Compose
-definition has been updated to include a Mercure service.
+:ref:`Symfony Flex <symfony-flex>` has automatically installed and configured MercureBundle.
+It also created (if needed) and configured a Docker Compose definition that provides a Mercure service.
 Run ``docker-compose up`` to start it.
 
 Configuration