Mark breadcrumb handler as optional

Author: stayallive

docs/platforms/php/guides/symfony/integrations/monolog.mdx

@@ -12,15 +12,15 @@ sentry:
     register_error_handler: false # Disables the ErrorListener, ExceptionListener and FatalErrorListener integrations of the base PHP SDK
 
 services:
-    # Configure the breadcrumb handler as a service
+    # (Optionally) Configure the breadcrumb handler as a service (needed for the breadcrumb Monolog handler)
     Sentry\Monolog\BreadcrumbHandler:
         arguments:
             - '@Sentry\State\HubInterface'
             - !php/const Monolog\Logger::INFO # Configures the level of messages to capture as breadcrumbs
 
 monolog:
     handlers:
-        # Register the breadcrumb handler as a Monolog handler
+        # (Optionally) Register the breadcrumb handler as a Monolog handler
         sentry_breadcrumbs:
             type: service
             name: sentry_breadcrumbs