Updated the message with the related method

Author: dnyomo

app/code/Magento/CatalogGraphQl/Model/Resolver/Products/DataProvider/ProductSearch.php

@@ -156,6 +156,7 @@ private function getSortOrderArray(SearchCriteriaInterface $searchCriteria)
             foreach ($sortOrders as $sortOrder) {
                 // I am replacing _id with entity_id because in ElasticSearch _id is required for sorting by ID.
                 // Where as entity_id is required when using ID as the sort in $collection->load();.
+                // @see \Magento\CatalogGraphQl\Model\Resolver\Products\Query\Search::getResult
                 if ($sortOrder->getField() === '_id') {
                     $sortOrder->setField('entity_id');
                 }