Document new [p]set usebuttons command (#5885)

docs/cog_guides/core.rst

@@ -3956,6 +3956,33 @@ Otherwise, the colour used will be the colour of the bot's top role.
 **Example:**
     - ``[p]set usebotcolour``
     
+.. _core-command-set-usebuttons:
+
+""""""""""""""
+set usebuttons
+""""""""""""""
+
+.. note:: |owner-lock|
+
+**Syntax**
+
+.. code-block:: none
+
+    [p]set usebuttons [use_buttons]
+    
+**Description**
+
+Set a global bot variable for using buttons in menus. When enabled, all usage of
+cores menus API will use buttons instead of reactions. This defaults to False.
+Using this without a setting will toggle.
+
+**Examples:**
+- ``[p]set usebuttons True`` - Enables using buttons.
+- ``[p]helpset usebuttons`` - Toggles the value.
+
+**Arguments:**
+    - ``[use_buttons]`` - Whether to use buttons. Leave blank to toggle.
+
 .. _core-command-shutdown:
 
 ^^^^^^^^