Add support to enable sorting on string

Author: developerEinpix

src/DependencyInjection/Configuration.php

@@ -38,6 +38,7 @@ public function getConfigTreeBuilder(): TreeBuilder
                                         ->scalarNode('name')->end()
                                         ->scalarNode('type')->end()
                                         ->booleanNode('facet')->end()
+                                        ->booleanNode('sort')->end()
                                         ->booleanNode('optional')->end()
                                     ->end()
                                 ->end()