Fix syntax and add a missing return description for inline documentation introduced in [32644] for WP_Users_List_Table.

See #25408. See #32246.

Built from https://develop.svn.wordpress.org/trunk@32670


git-svn-id: http://core.svn.wordpress.org/trunk@32640 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-users-list-table.php

@@ -472,12 +472,12 @@ class WP_Users_List_Table extends WP_List_Table {
 	}
 
 	/**
-	 * Get name of default primary column
+	 * Get the name of the default primary column.
 	 *
 	 * @since 4.3.0
 	 * @access protected
 	 *
-	 * @return string
+	 * @return string Name of the default primary column, in this case, 'username'.
 	 */
 	protected function get_default_primary_column_name() {
 		return 'username';