Fix Docker usage example (#36)

Author: Wirone

index.rst

@@ -49,6 +49,7 @@ PHP CS Fixer can be run in a Docker container.
 You can use pre-built Docker images to run ``php-cs-fixer``.
 
 .. code:: console
+
     docker run -v $(pwd):/code ghcr.io/php-cs-fixer/php-cs-fixer:${FIXER_VERSION:-3-php8.3} fix src
 
 ``$FIXER_VERSION`` used in example above is an identifier of a release you want to use, which is based on Fixer and PHP versions combined. There are different tags for each Fixer's SemVer level and PHP version with syntax ``<php-cs-fixer-version>-php<php-version>``. For example: