[docs] Fixed minor formatting issue in importing_users.rst

Author: nemesifier

docs/user/importing_users.rst

@@ -70,12 +70,12 @@ auto-generated and contents of these emails can be customized too.
 
 Here are some defined settings for doing that:
 
-    - :ref:`OPENWISP_RADIUS_BATCH_MAIL_SUBJECT
-      <openwisp_radius_batch_mail_subject>`
-    - :ref:`OPENWISP_RADIUS_BATCH_MAIL_MESSAGE
-      <openwisp_radius_batch_mail_message>`
-    - :ref:`OPENWISP_RADIUS_BATCH_MAIL_SENDER
-      <openwisp_radius_batch_mail_sender>`
+- :ref:`OPENWISP_RADIUS_BATCH_MAIL_SUBJECT
+  <openwisp_radius_batch_mail_subject>`
+- :ref:`OPENWISP_RADIUS_BATCH_MAIL_MESSAGE
+  <openwisp_radius_batch_mail_message>`
+- :ref:`OPENWISP_RADIUS_BATCH_MAIL_SENDER
+  <openwisp_radius_batch_mail_sender>`
 
 Using the admin interface
 -------------------------