Add a text area for details meta on a WooCommerce product category edit term page

functions.php

<?php

add_action( 'product_cat_edit_form_fields', 'wpm_product_cat_edit_details_meta' );
/**
 * Add a details metabox to the Edit Product Category page.
 *
 * For adding a details metabox to the WordPress admin when
 * editing an existing product category in WooCommerce.
 *
 * @param  object $term The existing term object.
 */
function wpm_product_cat_edit_details_meta( $term ) {

	$product_cat_details = get_term_meta( $term->term_id, 'details', true );

	if ( ! $product_cat_details ) {
		$product_cat_details = '';
	}

	$settings = array( 'textarea_name' => 'wpm-product-cat-details' );
	?>
	<tr class="form-field">
		<th scope="row" valign="top"><label for="wpm-product-cat-details"><?php esc_html_e( 'Details', 'wpm' ); ?></label></th>
		<td>
			<?php wp_nonce_field( basename( __FILE__ ), 'wpm_product_cat_details_nonce' ); ?>
			<?php wp_editor( wpm_sanitize_details( $product_cat_details ), 'product_cat_details', $settings ); ?>
			<p class="description"><?php esc_html_e( 'Detailed category info to appear below the product list','wpm' ); ?></p>
		</td>
	</tr>
	<?php

}