added missing article

Author: pabel-rh

modules/customization/proc-customize-rhdh-sidebar-menuitems.adoc

@@ -93,22 +93,26 @@ dynamicPlugins:
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-. To ensure that a menu item is identified as a main menu item, you must add `default.` prefix to its key. For example:
+. To ensure that a menu item is identified as a main menu item, you must add the `default.` prefix to its key. For example:
 +
 --
 .Example configuration of main menu items in sidebar navigation
 [source,yaml]
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 dynamicPlugins:
   frontend:
-    default.main-menu-items: # key for configuring static main menu items
-      default.<menu_item_name>: # key of the menu item configuration. `default.` prefix is required for a main menu item key <1>
-        parent: my_menu_group # optional, specifies the parent menu item for this item
-        priority: 10 # optional, specifies the order of this menu item within its menu level
-      default.<menu_group_parent_item_name>: # must be configured if it is specified as the parent of any menu items. `default.` prefix is required for a main menu item key
-        icon: my_menu_group_icon # required for parent menu items, defines the icon for the menu group
-        title: my_menu_group_title # required for parent menu items, defines the icon for the menu group
-        priority: 100 # optional, specifies the order of the parent menu item in the sidebar
+    default:
+      main-menu-items: # key for configuring static main menu items
+        menuItems: 
+          default: # `default.` prefix is required for a main menu item key <1>
+            <menu_item_name>: # key of the menu item configuration.
+              parent: my_menu_group # optional, specifies the parent menu item for this item
+              priority: 10 # optional, specifies the order of this menu item within its menu level
+            default: # `default.` prefix is required for a main menu item key <1>
+              <menu_group_parent_item_name>: # must be configured if it is specified as the parent of any menu items.
+                icon: my_menu_group_icon # required for parent menu items, defines the icon for the menu group
+                title: my_menu_group_title # required for parent menu items, defines the icon for the menu group
+                priority: 100 # optional, specifies the order of the parent menu item in the sidebar
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