$eavSetup->addAttribute(
            MagentoCatalogModelCategory::ENTITY,
            'customattribute',
   [
     'group' => 'Custom Group',
                 'type' => 'varchar',
                 'label' => 'Custom Group',
                 'input' => 'textarea',
     'source' => '',
                 'required' => false,
                 'sort_order' => 49,
                 'global' => MagentoEavModelEntityAttributeScopedAttributeInterface::SCOPE_STORE,
     'wysiwyg_enabled' => true,
                 'is_used_in_grid' => true,
                 'is_visible_in_grid' => false,
                 'is_filterable_in_grid' => true
            ]
        );