Adds box.schema.user.enable and box.schema.user.disable methods (#5123)

* Added ``box.schema.user.enable`` and ``box.schema.user.disable`` methods description to Submodule ``box.schema``
* 2 new files ("user_enable.rst" and user_disable.rst") added to the ``box.schema`` submodule.
* Files describe methods that grant and revoke permissions.
* References added to existing files ("box_schema.rst", "user_grant.rst", "user_revoke.rst")
Fixes #5122

Author: AArdeev

doc/reference/reference_lua/box_schema.rst

@@ -53,6 +53,12 @@ Below is a list of all ``box.schema`` functions.
         *  - :doc:`./box_schema/user_revoke`
            - Revoke privileges from a user or a role
 
+        *  - :doc:`./box_schema/user_enable`
+           - Grant ``usage`` and ``session`` permissions
+
+        *  - :doc:`./box_schema/user_disable`
+           - Revoke ``usage`` and ``session`` permissions
+
         *  - :doc:`./box_schema/user_password`
            - Get a hash of a user's password
 
@@ -105,6 +111,8 @@ Below is a list of all ``box.schema`` functions.
     box_schema/user_exists
     box_schema/user_grant
     box_schema/user_revoke
+    box_schema/user_enable
+    box_schema/user_disable
     box_schema/user_password
     box_schema/user_passwd
     box_schema/user_info

doc/reference/reference_lua/box_schema/user_disable.rst

@@ -0,0 +1,31 @@
+.. _box_schema-user_disable:
+
+===============================================================================
+box.schema.user.disable()
+===============================================================================
+
+.. module:: box.schema
+
+.. function:: box.schema.user.disable(username)
+
+    Revokes ``usage`` and ``session`` permissions from the subject user. Equivalent to the following call:
+
+    ..  code-block:: lua
+
+        box.schema.user.revoke(username, 'usage,session', 'universe', nil, {if_not_exists = true})
+
+    .. NOTE::
+
+       * ``session`` - allows the binary protocol layer (iproto) to authenticate the user
+
+       * ``usage`` - lets user use their privileges on database objects (such as read, write and alter space)
+
+    For more information about revoking permissions see section :ref:`box.schema.user.revoke <box_schema-user_revoke>`.
+
+    :param string username: the name of the subject user
+ 
+    :return: (if success) nothing
+
+    Possible errors:
+
+    * ``NO_SUCH_USER`` - in case the subject user is not found.

doc/reference/reference_lua/box_schema/user_enable.rst

@@ -0,0 +1,31 @@
+.. _box_schema-user_enable:
+
+===============================================================================
+box.schema.user.enable()
+===============================================================================
+
+.. module:: box.schema
+
+.. function:: box.schema.user.enable(username)
+
+    Grants ``usage`` and ``session`` permissions to the subject user. Equivalent to the following call:
+
+    ..  code-block:: lua
+
+        box.schema.user.grant(username, 'usage,session', 'universe', nil, {if_not_exists = true})
+
+    .. NOTE::
+
+       * ``session`` - allows the binary protocol layer (iproto) to authenticate the user
+
+       * ``usage`` - lets user use their privileges on database objects (such as read, write and alter space)
+
+    For more information about granting permissions see section :ref:`box.schema.user.grant <box_schema-user_grant>`.
+
+    :param string username: the name of the subject user
+ 
+    :return: (if success) nothing
+
+    Possible errors:
+
+    * ``NO_SUCH_USER`` - in case the subject user is not found.

doc/reference/reference_lua/box_schema/user_grant.rst

@@ -31,7 +31,7 @@ box.schema.user.grant()
 
     **Variation:** instead of
     :samp:`box.schema.user.grant('{username}','usage,session','universe',nil,` :code:`{if_not_exists=true})`
-    say :samp:`box.schema.user.enable('{username}')`.
+    say :samp:`box.schema.user.enable('{username}')` (see section :ref:`box.schema.user.enable <box_schema-user_enable>`).
 
     The possible options are:
 

doc/reference/reference_lua/box_schema/user_revoke.rst

@@ -31,7 +31,7 @@ box.schema.user.revoke()
 
     **Variation:** instead of
     :samp:`box.schema.user.revoke('{username}','usage,session','universe',nil,` :code:`{if_exists=true})`
-    say :samp:`box.schema.user.disable('{username}')`.
+    say :samp:`box.schema.user.disable('{username}')` (see section :ref:`box.schema.user.disable <box_schema-user_disable>`).
 
     **Example:**