Issue #3058409 by guilhermevp, joachim, ravi.shankar, quietone, init90, andregp: TermStorage::loadTree() doesn't document what the return array is keyed by

(cherry picked from commit 1de8b6a8efb1231e040eefc896741c1eb94f64fe)

core/modules/taxonomy/src/TermStorageInterface.php

@@ -87,7 +87,8 @@ interface TermStorageInterface extends ContentEntityStorageInterface {
    *   numbers of terms. Defaults to FALSE.
    *
    * @return object[]|\Drupal\taxonomy\TermInterface[]
-   *   An array of term objects that are the children of the vocabulary $vid.
+   *   A numerically indexed array of term objects that are the children of the
+   *   vocabulary $vid.
    */
   public function loadTree($vid, $parent = 0, $max_depth = NULL, $load_entities = FALSE);