Add Symfony Notifier integration

Integrated Symfony Notifier into the project by adding it to `composer.json` and creating a configuration file `notifier.yaml`. Updated `symfony.lock` to include the recipe configuration for Notifier. Minor documentation formatting issues were also fixed in `index.rst`.

composer.json

@@ -16,8 +16,8 @@
         "ext-zlib": "*",
         "champs-libres/wopi-bundle": "dev-master@dev",
         "champs-libres/wopi-lib": "dev-master@dev",
-        "doctrine/doctrine-bundle": "^2.1",
         "doctrine/data-fixtures": "^1.8",
+        "doctrine/doctrine-bundle": "^2.1",
         "doctrine/doctrine-migrations-bundle": "^3.0",
         "doctrine/orm": "^2.13.0",
         "erusev/parsedown": "^1.7",
@@ -58,6 +58,7 @@
         "symfony/messenger": "^5.4",
         "symfony/mime": "^5.4",
         "symfony/monolog-bundle": "^3.5",
+        "symfony/notifier": "^5.4",
         "symfony/options-resolver": "^5.4",
         "symfony/process": "^5.4",
         "symfony/property-access": "^5.4",