Updates description by comments

Fixes #5123

Author: AArdeev

doc/reference/reference_lua/box_schema/user_disable.rst

@@ -8,23 +8,16 @@ box.schema.user.disable()
 
 .. function:: box.schema.user.disable(username)
 
-    Deactivate a user. If :samp:`'{username}'` does not exist, an error is returned.
+    Initiates the :samp:`box.schema.user.revoke('{username}','usage,session','universe',nil,` :code:`{if_exists=true})`
+    (see section :ref:`box.schema.user.revoke <box_schema-user_revoke>`).
 
     :param string username: the name of a user to be deactivated
 
-    :return: (if success) ``---``
-
-             (if failure) ``error: 'User '{username}' doesn''t exist'``
+    :return: ``---``
 
     **Example:**
 
         ..  code-block:: lua
 
-            box.schema.user.disable (username)
-            
+            box.schema.user.disable (username)       
             ---
-
-    **Variation:** instead of :samp:`box.schema.user.disable('{username}')`, say
-    :samp:`box.schema.user.revoke('{username}','usage,session','universe',nil,` :code:`{if_exists=true})`
-    (see section :ref:`box.schema.user.revoke <box_schema-user_revoke>`).
-   

doc/reference/reference_lua/box_schema/user_enable.rst

@@ -8,20 +8,18 @@ box.schema.user.enable()
 
 .. function:: box.schema.user.enable(username)
 
-    Activate deactivated user. If :samp:`'{username}'` does not exist, it will be created. If :samp:`'{username}'` is already active, nothing changes.
+    Initiates the :samp:`box.schema.user.grant('{username}','usage,session','universe',nil,` :code:`{if_not_exists=true})` method
+    (see section :ref:`box.schema.user.grant <box_schema-user_grant>`).
 
-    :param string username: the name of a user to be activated
+    :param string username: the name of the subject user
 
-    :return: ``---``
+    :return: (if success) ``---``
+
+             (if failure) ``error: User 'username' is not found``
 
     **Example:**
 
         ..  code-block:: lua
 
-            box.schema.user.enable (username)
-            
+            box.schema.user.enable (username)            
             ---
-
-    **Variation:** instead of :samp:`box.schema.user.enable('{username}')`, say
-    :samp:`box.schema.user.grant('{username}','usage,session','universe',nil,` :code:`{if_not_exists=true})`
-    (see section :ref:`box.schema.user.grant <box_schema-user_grant>`).