fix(argonaut) remove the mention of argonaut-user-reminder

Signed-off-by: Benoit Mortier <benoit.mortier@fusiondirectory.org>

source/fusiondirectory/plugins/user-reminder/functionalities.rst

-Functionalities
-===============
-
-The user reminder plugin is used in conjunction with the `argonaut-user-reminder program <https://argonaut-user-manual.readthedocs.io/en/1.4/applications/user-reminder/index.html>`_
-
-

source/fusiondirectory/plugins/user-reminder/index.rst

@@ -9,5 +9,4 @@ FusionDirectory Plugins user-reminder
    description
    installation
    configuration
-   functionalities
    reminderTask