Revert "Add docs for enable_content_listener option."

This reverts commit ffa4f4e.

Author: dbu

bundles/seo/configuration.rst

@@ -128,16 +128,3 @@ form_group
 
 The name of the form group of the group provided by the Sonata Admin
 Extension.
-
-``enable_content_listener``
-"""""""""""""""""""""""""""
-
-.. versionadded:: 1.2
-    The ``enable_content_listener`` configuration key was introduced in SeoBundle 1.2
-
-**type**: ``boolean`` **default**: ``true``
-
-Whether or not the ``Symfony\Cmf\Bundle\SeoBundle\EventListener\ContentListener`` should be loaded
-as a ``kernel.request`` listener. The ContentListener is responsible for extracting SEO data from
-CMF content documents. Set this to false to disable the listener. If you want to use your own content listener
-you will need to register your listener as a service and tag it as a ``kernel.request`` listener.